Field Office Guide to Climatic Data
Table of Contents
Introduction [TOC]
The Natural Resources Conservation Service is charged with
management of not only soil, but all five SWAPA resources (soil,
water, air, plants, animals), and human considerations. SWAPA
management requires an understanding of the resources, as well as
interactions between resources. Many concerns about the resources
can be addressed through climate information and specific climatic
data.
Climate is an important factor driving the agriculture of a given
region (along with soils, water available for irrigation, societal
influences, economics, others). Under many situations, climate is
THE determining factor which defines which crops can be grown in an
area. For instance, although the soils and economics of North Dakota
may support growing cotton, the climate there (specifically
temperature and precipitation) would not allow cotton to grow and
mature.
This publication concerning climatic data is oriented to the NRCS
role in American agriculture and natural resource conservation. It
describes the NRCS National Water & Climate Center (NWCC) and
its network of liaisons in each NRCS state office.
How to Use this Guide [TOC]
This guide is divided into 7 sections. Section 1 contains
detailed information about climatic data elements, measurement
methods, and problems associated with collecting climatic data.
Sections 2, 3, and 4 provide material to help understand data
collection systems. Section 5, Climate Terminology, contains
definitions of climatic terms. Section 6 explains how climatic
information can be obtained. Climatic data needs associated with a
particular conservation practice are listed in Section 7.
1 Climatic Data Element Descriptions, Measurement
Methods, and Errors Associated with it's Collection. [TOC]
The following description of climatic data elements is a
condensation of the material contained in the National Weather
Service Observing Handbook No.2, Cooperative Station Observations,
the Weather Station Handbook an Interagency Guide for Wildland
Managers, and the American Meteorological Society Glossary of
Meteorology.
Statistical analysis of climatic data generates descriptive
information which reflects the average atmospheric conditions at a
location, as well as generating probabilities that extreme events
will occur. Any statistical analysis of climatic data, due mainly to
the limited number of samples available, must follow the rules for
statistical analysis. An important rule governing small sample
analysis requires a minimum of 30 samples. This does not mean that
climatic data with less than 30 years of data can not be analyzed,
but that some adjustment be made to estimate what a 30 sample set
would produce.
AIR TEMPERATURE - Temperature is a measure of the hotness
or coldness of air. It is measured on some definitive temperature
scale. Two scales are commonly used. The Fahrenheit and Centigrade
temperature scales establish the freezing of water at 32/0 degrees
respectively and boiling point at 212/100 degrees respectively. The
Fahrenheit scale is used most frequently in the US and Centigrade
throughout the rest of the world. Air temperature is usually
measured with either a liquid-in-glass maximum and minimum
thermometer mounted in a vented, wooden box or with an electronic
sensor.
It is important that thermometers be shaded from sunlight to
avoid an erroneously high measured temperature. Instrument shelters
are designed to rectify this problem. For more information on
instrument shelters, see the Weather Station Handbook - an
Interagency Guide for Wildland Managers.
EVAPORATION - Evaporation is the physical process by which
a liquid is transformed to a gaseous state. Evaporation is
influenced by solar radiation, air temperature, vapor pressure,
wind, and possibly atmospheric pressure. Evaporation varies with
latitude, altitude, season, time of day, and sky condition. Accurate
evaporation readings requires careful maintenance of an evaporation
pan which contains water. The water depth is measured daily and
adjusted for any precipitation which may occur.
PRECIPITATION - Precipitation refers to all forms of
water, liquid or solid, that fall from the atmosphere and reach the
ground. Precipitation includes, but is not limited to, rain,
drizzle, snow, hail, graupel, sleet, and ice crystals. It is one of
the most basic data elements collected by any climate station. Dew,
frost and rime are excluded, since they are a result of water vapor
in air condensing or freezing onto a surface.
The standard U.S. precipitation gage has an eight inch diameter
mouth and height of about 30 inches. Non-recording gages simply
collect precipitation; amount of precipitation must be measured by
an observer. Recording gages have instrumentation which records the
time, duration, and intensity of precipitation. Most recording gages
store information on a paper strip, which is generally changed
weekly by an observer. Precipitation intensity and duration, useful
information for many NRCS design activities, can be derived from
information gathered by precipitation gages.
The biggest factor in precipitation measurement error is wind.
Strong winds during precipitation events can cause considerable
differences between measured and actual precipitation. Measurement
errors can also result from small amounts of dew, frost, and rime
accidentally included in the total measured precipitation. Even with
careful placement, all gages underestimate the real
precipitation, particularly with snowfall.
NEW SNOW - New snow is the incremental amount of snow that
has fallen since the last snow depth observation. Delineating
between new snow and old snow presents a challenge. A snow board
(generally a sheet of plywood) can provide an artificial surface at
the top of the existing snow. Snow boards are laid on top of old
snow when there is any possibility of new snow falling. After each
observation of new snow, the board is cleaned and placed in a new
location. Board placement and measurement location are the greatest
source of error in determining new snow.
SNOW DEPTH - Snow depth is the actual depth of snow on the
ground at the time of measurement. Snow depth is usually measured
daily and determined to the nearest whole inch with a calibrated
stick, such as that used with the 8-inch non-recording rain gage, or
a ruler or yardstick. Snow should be measured in several locations
and averaged to avoid errors induced by drifted snow.
SNOW WATER EQUIVALENT - The water equivalent of snow is
the depth of water that would be obtained by melting the snow cover.
Water equivalent of snow is continuously measured (weighed) by
recording gages which are winterized with an antifreeze solution.
For non-recording gages, the snow catch collected by the standard
rain gage (with the funnel and small tube removed) is melted by
adding a known amount of warm water. The total amount is then
measured and the added amount of warm water subtracted to yield the
observed water equivalent. Most snow water equivalent measurement
errors are associated with not selecting a representative location
or the mechanics of subtracting water added to the total catch.
SOIL TEMPERATURE - Soil temperature measures the hotness
or coldness of soil. Soil temperature is very important to the
agricultural industry. Most seeds require a certain soil temperature
in order to germinate. Soil temperatures are commonly measured at 2,
4, 8, 20, 40, 60, and 120 inches with the 4 inch reading being the
most frequently observed. Readings are usually observed and recorded
daily. Maximum, minimum, and current temperatures are generally
recorded above 8 inches. At greater depths, where temperature
changes more slowly, only the current temperature is normally
recorded. Different species of plants have specific soil temperature
ranges in which they will grow.
SOLAR RADIATION - INCOMING - Incoming solar radiation is
the total electromagnetic radiation emitted by the sun striking the
earth. Much solar radiation is absorbed by air molecules, reflected
back into space, or refracted as it passes through the atmosphere. A
pyrheliometer measures the direct solar radiation that passes
through the atmosphere unimpeded. It consists of an enclosed
radiation sensing element with a small aperture through which the
direct solar rays enter. A pyranometer measures the combined
incoming direct solar radiation and diffuse sky radiation. It is
mounted such that it views the entire sky. Both instruments can be
connected to electronic recording devices to collect the
measurements. Solar radiation sensors must be cleaned regularly and
exposed properly to accurately measure solar radiation.
WIND - Wind is the motion of air relative to the surface
of the earth. Wind speed and direction, the two primary elements,
are usually measured with an anemometer and wind vane, respectively.
Wind speed is generally measured in miles per hour; direction is
measured in degrees to the nearest ten(s) (10 to 360) with 360
degrees being north, 90 degrees being east, 180 degrees representing
south, and 270 degrees being west. Wind measurement accuracy is
primarily influenced by sensor height and nearby objects.
2 Climate Station Metadata [TOC]
Climate Stations are locations at which climatic data are
gathered. Biographical and index information describing the climatic
station, called "Metadata", are used in conservation
applications and resource evaluations.
STATION ID - Identification number for the climate station
assigned by the agency responsible for the particular station.
STATION NAME - The full name of the climate station as
recognized by the agency responsible for the climate station.
STATION LATITUDE - Latitude defines a site's location
based on its relative distance from the equator going toward the
North or South poles. Station latitude is measured in degrees,
minutes, and seconds, with 0 degrees being on the equator, and 90
degrees north or south being the North and South Poles,
respectively. The latitude of a particular climate station is
determined by the agency managing the station and is generally
recorded to the nearest minute.
STATION LONGITUDE - Longitude defines a sites relative
distance, up to 180 degrees, west or east of a North-South line
running through Greenwich, England. The longitude of a particular
station is determined by the agency managing the station.
Measurement is generally made to the nearest minute.
STATION ELEVATION - The elevation of a climate station is
usually measured in feet above mean sea level.
3 Climatic Element [TOC]
A climatic element is a measured parameter which helps to specify
the climate of a specific location or region, such as precipitation,
temperature, wind speed and humidity. Descriptive terminology for
climatic elements are:
ELEMENT NAME - The full description of the element being
referenced at the climate station (i.e. maximum temperature).
ELEMENT ID - Is a shortened identifier for the element,
usually 4 characters in length (i.e. TMAX(maximum daily
temperature), TMIN(minimum daily temperature), PRCP(precipitation,
etc).
ELEMENT DURATION - The interval between
measurements of a data element. Common data element durations
available for the station could include monthly, daily, or hourly.
4 Climate Data Measurement Networks [TOC]
National Weather Service Cooperative Station Network
Cooperative stations generally record daily precipitation and/or
maximum and minimum temperature. Several other weather parameters
may also be observed, such as evaporation, wind movement, and soil
temperature.
The following table lists specific climate elements and the
number of National Weather Service stations which measure it:
DATA ELEMENT NUMBER OF
MEASURING STATIONS
Precipitation 10,700
Snow Depth 10,700
New Snow 10,700
Temperature 7,000
Wind 500
Evaporation 300
Incoming Solar Radiation 250
Soil Temperature 300
Natural Resources Conservation Service (NRCS)
The NRCS operates an automated network of approximately 600
stations in the western U.S. called SNOTEL (SNOwpack TELemetry).
Begining October 1st these stations report accumulated seasonal
precipitation , snow water equivalent, and temperature (maximum,
minimum, current and average) daily. This network was established in
the late 1970s to support water supply forecasting. It uses
meteorburst technology to transmit data from remote sites to data
gathering locations. SNOTEL augmented and partially replaced the
cooperative network of manual snow courses that NRCS acquired and
established the mid 1930s.
5 Climate Glossary [TOC]
The following lists terms which provide descriptive information
for climatic datasets:
ALBEDO - The ratio of the amount of radiation reflected by
a body to the amount of radiation incident upon it; expressed as a
percentage.
CLIMATE - the synthesis of weather, or averaging of
weather conditions over a given time period.
DEGREE DAYS, COOLING - A value used to estimate the
energy requirements for air conditioning of homes and buildings. One
cooling degree day is given for each degree the daily mean
temperature is above 75 degrees Fahrenheit.
DEGREE DAYS, GROWING - Growing degree days (GDD)
measures the day to day accumulation of the difference between the
average daily temperature and a threshold temperature for a specific
crop. GDD's give an indication of the amount of heat available for
crop growth.
DEGREE DAYS, HEATING - A value used to estimate the
energy requirements for heating homes and buildings. One heating
degree day is given for each degree the daily mean temperature is
below 65 degrees Fahrenheit.
DEWPOINT - The temperature to which air is cooled for
water vapor to begin condensing.
DRIZZLE - Very small, numerous, and uniformly dispersed
water drops that may appear to float while following air currents.
Unlike fog droplets, drizzle falls to the ground.
DURATION - the period or time increment to which an
observed or computed value applies.
EVAPORATION - Evaporation is the physical process by which
a liquid is transformed to a gaseous state.
EVAPOTRANSPIRATION (ET) - The combined processes of
evaporation and transpiration.
FOG - A visible collection of minute water droplets
suspended in the atmosphere near the earth's surface. Fog reduces
visibility below one kilometer (0.62 miles).
FREEZE - A freeze occurs at any time the surface air
temperature reaches 28 degrees or less. This temperature causes
damage to most vegetation except certain species which are resistant
to freezing.
FREEZE FREE PERIOD - Freeze free period is the number of
consecutive days where the air temperature does not fall below 28
degrees Fahrenheit.
FREEZE, KILLING - A killing freeze occurs at or
below 24 degrees Fahrenheit and causes permanent damage to almost
all vegetation.
FREEZE FREE PERIOD, KILLING - Killing freeze free period
is the number of consecutive days where the air temperature does not
fall below 24 degrees Fahrenheit.
FROST - Frost is the process of deposition of frozen
atmospheric water vapor on surfaces whose surface air temperature is
below 32 degrees Fahrenheit. A frost can occur at any time the
surface air temperature falls to 32 degrees Fahrenheit or less. This
temperature may cause damage to very young vegetation or vegetation
that has no resistance to frost. Most fruit falls in this category.
FROST FREE PERIOD - Frost free period is the number of
consecutive days where the surface air temperature does not fall
below 32 degrees Fahrenheit.
FROST, FIRST - First Frost is the first date following the
growing season that the minimum temperature drops below an index
temperature, usually 32 degrees Fahrenheit. The first frost usually
occurs in the fall of the year, but it may occur during the winter
months, or in some locations may not occur at all.
FROST, LAST - Last Frost is the last date preceding
the growing season that the minimum temperature drops below an index
temperature, usually 32 degrees Fahrenheit. The last frost usually
occurs in the spring of the year but may occur very early in the
summer or not at all in some locations. First and Last frosts are
analyzed at three temperatures (32, 28, and 24 degrees Fahrenheit)
specifically relating to damage caused to vegetation by the
sub-freezing temperatures.
GROWING SEASON - Growing Season is the number of
consecutive days where the temperature has not gone below an index
temperature for specific vegetation. If vegetation is more resistant
to cold temperatures the index temperature would be lower. The index
temperatures used in growing season analysis usually include 24, 28,
and 32 degrees Fahrenheit.
GROWING SEASON PERIOD - Growing Season Period is the
period of time, beginning date and ending date, that defines the
period that the temperature has not dropped below the index
temperature.
HAIL - Precipitation in the form of balls or irregular
lumps of ice with a diameter of 5 mm or more, always produced by
convective clouds, nearly always cumulonimbus.
HUMIDITY, RELATIVE - A measure of the amount of
water in the air compared to the amount of water vapor the air has
the potential to hold. (Note: the potential of air to hold water
changes with air temperature. Therefore, relative humidity can
change as air temperature changes without an actual change in the
amount of water vapor.)
INDEX TEMPERATURE - A temperature which denotes the
beginning of a specific event such as 28 degrees Fahrenheit. The 28
degree temperature denotes a freeze that can damage plants.
NORMAL - "Normal" is an average of any of the
climatic elements calculated for a specific time period. The
beginning and ending years of the normal period are established by
the World Meteorological Organization. This organization has defined
the current standard averaging period for "Normals" as
1971 through 2000. Normals have been established as the standard
period that will be used in analysis of climatic data to allow for
comparable descriptive information representative of average
conditions over the time period.
PERIOD OF RECORD - The time interval during which
meteorological and climatic data have been gathered at a climatic
station.
PRECIPITATION - Precipitation refers to all forms of
water, liquid or solid, that fall from the atmosphere and reach the
ground. Precipitation includes, but is not limited to, rain,
drizzle, snow, hail, grapple, sleet, and ice crystals.
PROBABILITY - Probability is a statistical process that
provides for the analysis of data to determine the potential of an
individual value to occur at a specified time, in a given year, or
in a given period of time. An example might indicate that a certain
value has a 10 percent chance of occurrence in any year, or that the
value has a chance of returning once in a period of ten years.
RAIN - Precipitation in the form of liquid water drops
which have diameters greater than 0.02 in (0.5 mm).
WIND ROSES - A type of analysis that describes wind
measurements graphically and tabularly as a combination of the
cardinal direction that the wind was coming from and the average
speed from that direction for a particular time interval.
SLEET - A type of precipitation consisting of transparent
or translucent pellets of ice 5 mm or less in diameter. Sleet forms
when raindrops fall through a layer of below-freezing air near the
earth's surface.
SNOW WATER EQUIVALENT - The water equivalent of snow is
the depth of water that would be obtained by melting the snow cover.
SOLAR RADIATION - The total amount of energy emitted by
the sun.
SOLAR RADIATION, INCOMING - Incoming solar
radiation is the total electromagnetic radiation emitted by the sun
striking the earth.
TEMPERATURE - Temperature is a measure of the internal
energy of molecular motion in a substance.
THRESHOLD TEMPERATURE - A temperature that denotes the
boundary condition for a specific event. For example, a crop
specific temperature below which the growth of that crop is minimal.
TRANSPIRATION - The process by which water in plants is
transferred to the atmosphere as water vapor.
WEATHER - the instantaneous or short-term state of the
atmosphere.
WIND - Wind is the motion of air relative to the surface
of the earth.
6 National Water & Climate Center/Climatic Data Access
Network [TOC]
The Natural Resources Conservation Service's National Water &
Climate Center was created to provide the climatic data analyses
needed by NRCS employees and offices to perform conservation
activities. Each state and national center has been assigned a
Climatic Data Liaison (CDL) to deliver climatic data to field
offices as well as other offices in the state requiring climatic
data. These Climatic Data Liaisons make up what is known as the
Climatic Data Access Network (CDAN). CDAN provides a corp of
knowledgeable individuals to assist NRCS field offices in the
analysis of climatic data.
The mission of NWCC/CDAN is to access, obtain, evaluate, manage,
and disseminate the climatic data needed to support agency programs
and activities nationally. The Vision of NWCC/CDAN is "A
dynamic, agency-wide climate service network -- providing data and
analyses required for integrated ecosystem management."
A wide variety of daily, monthly, and annual data are available
through NWCC/CDAN, including air and soil temperature, evaporation,
wind movement, snow depth, snow water equivalent and precipitation.
Climatic interpretations (probabilities and statistical summaries)
for temperature and precipitation, growing season and construction
information, rainfall frequency, and information for agronomic and
engineering models are available through the Network.
The following examples demonstrate the variety of information
available through NWCC/CDAN:
TEMPERATURE AND PRECIPITATION SUMMARY (TAPS) [TOC]
The TAPS table gives a month by month summary and probability
analysis of temperature and precipitation.
TAPS Station : DECORAH, 192110
Start yr. - 1971 End yr. - 2000
Temperature: 30 years available out of 30 requested in this analysis
Precipitation: 30 years available out of 30 requested in this analysis
| Temperature | Precipitation
|-----------------------------------|----------------------------
| | | |2 yrs in 10| | |2 yrs in 10|
| | | | will have | avg | | will have |avg no |
|-----|-----|-----|-----------|no of| |-----------|of days|avg
Month | avg | avg | avg |max | min |grow | avg | less| more|w/ 0.10|snow-
|daily|daily| |temp.|temp.|deg | | than| than|inch or|fall
| max | min | |>than|<than|days*|(in.)|(in.)|(in.)|more
------------------------------------------------------------------------------
January | 23.7| 5.3| 14.5| 49 | -29 | 1| 0.74| 0.27| 1.14| 2 | 7.0
February | 29.6| 10.7| 20.1| 54 | -22 | 3| 0.82| 0.32| 1.29| 2 | 7.2
March | 42.0| 23.6| 32.8| 73 | -10 | 55| 1.89| 1.05| 2.64| 4 | 7.5
April | 58.2| 36.3| 47.2| 84 | 14 | 256| 3.42| 1.96| 4.71| 6 | 1.6
May | 70.8| 47.7| 59.2| 89 | 27 | 597| 3.82| 2.60| 4.94| 7 | 0.0
June | 79.7| 56.7| 68.2| 95 | 39 | 846| 4.20| 2.29| 5.89| 6 | 0.0
July | 83.7| 61.4| 72.6| 97 | 46 | 1010| 3.99| 2.28| 5.51| 6 | 0.0
August | 81.5| 59.0| 70.3| 95 | 42 | 937| 4.03| 2.04| 5.76| 6 | 0.0
September | 72.7| 50.7| 61.7| 91 | 29 | 651| 3.93| 1.53| 5.95| 6 | 0.0
October | 61.0| 39.9| 50.5| 84 | 18 | 339| 2.27| 1.07| 3.31| 4 | 0.2
November | 43.8| 27.0| 35.4| 67 | 1 | 65| 1.68| 0.65| 2.64| 4 | 3.4
December | 28.3| 12.1| 20.2| 56 | -21 | 5| 1.21| 0.63| 1.73| 3 | 9.7
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
Yearly : |-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
Average | 56.3| 35.9| 46.1| --- | --- | --- | --- | --- | --- | --- | ---
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
Extreme | 101| -39| --- | 98 | -31 | --- | --- | --- | --- | --- | ---
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
Total | --- | --- | --- | --- | --- | 4764|32.01|26.89|36.67| 56 | 36.5
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------
------------------------------------------------------------------------------
*A growing degree day is a unit of heat available for plant growth.
It can be calculated by adding the maximum and minumum daily temperatures,
dividing the sum by 2, and subtracting the temperature below which growth
is minimal for the principal crops in the area (Threshold : 40.0 deg. F)
FROST FREE DAYS (FROST) [TOC]
The FROST table provides information on the average date of the
last temperature below 24, 28, and 32 degrees Fahrenheit in the
spring, and the average date of the first temperature below 24, 28,
and 32 degrees Fahrenheit in the fall, at probabilities of 10, 20,
and 50%.
FROST Station : DECORAH, 192110
Start yr. - 1971 End yr. - 2000
Requested years of data: 30 Available years of data: 30
Spring: Missing data years 24 deg = 0, 28 deg = 0, 32 deg = 0
Years with no occurrence 24 deg = 0, 28 deg = 0, 32 deg = 0
Data years used 24 deg = 30, 28 deg = 30, 32 deg = 30
Fall: Missing data years 24 deg = 1, 28 deg = 1, 32 deg = 1
Years with no occurrence 24 deg = 0, 28 deg = 0, 32 deg = 0
Data years used 24 deg = 29, 28 deg = 29, 32 deg = 29
------------------------------------------------------------------------
| Temperature
---------------------------|--------------------------------------------
Probability | 24F or lower | 28F or lower | 32F or lower |
---------------------------|--------------|--------------|--------------
| | |
Last freezing temperature | | |
in spring: | | |
| | |
1 year in 10 later than-- | April 22 | May 9 | May 22
| | |
2 year in 10 later than-- | April 17 | May 3 | May 16
| | |
5 year in 10 later than-- | April 8 | April 23 | May 5
| | |
First freezing temperature | | |
in fall: | | |
| | |
1 yr in 10 earlier than-- | October 8 |September 26 |September 23
| | |
2 yr in 10 earlier than-- | October 13 | October 1 |September 26
| | |
5 yr in 10 earlier than-- | October 23 | October 12 | October 4
| | |
------------------------------------------------------------------------
GROWING SEASON (GROWTH) [TOC]
The GROWTH table gives average length of growing season using
three index temperatures (32, 28, and 24 degrees Fahrenheit) at
10, 20, 50, 80, and 90% probabilities.
GROWTH Station : DECORAH, 192110
Start yr. - 1971 End yr. - 2000
Requested years of data: 30 Available years of data: 30
Missing data years 24 deg = 1, 28 deg = 1, 32 deg = 1
Years with no occurrence 24 deg = 0, 28 deg = 0, 32 deg = 0
Data years used 24 deg = 29, 28 deg = 29, 32 deg = 29
------------------------------------------------------------------------
| Daily Minimum Temperature
---------------------------|--------------------------------------------
Probability | # days > 24F | # days > 28F | # days > 32F
| | |
9 years in 10 | 177 | 148 | 131
| | |
8 years in 10 | 184 | 156 | 138
| | |
5 years in 10 | 197 | 170 | 151
| | |
2 years in 10 | 210 | 185 | 163
| | |
1 year in 10 | 217 | 193 | 170
| | |
---------------------------|--------------|--------------|--------------
WETLANDS DETERMINATION (WETS) [TOC]
The WETS table gives a month by month summary and probability analysis of
temperature and precipitation. The table also provides average length of
growing season using three index temperatures (32, 28, and 24 degrees
Fahrenheit) at 50 and 70% probabilities.
WETS Station : DECORAH, 192110
Start yr. - 1971 End yr. - 2000
Temperature: 30 years used out of 30 requested in this analysis
Precipitation: 30 years used out of 30 requested in this analysis
| Temperature | Precipitation
|-----------------|------------------
| | | | |3 yrs in 10|
| | | | | will have |
|-----|-----|-----| |-----------|
Month | avg | avg | avg | avg | less| more|
|daily|daily| | | than| than|
| max | min | |(in.)|(in.)|(in.)|
----------------------------------------------|
January | 23.7| 5.3| 14.5| 0.74| 0.37| 0.96|
February | 29.6| 10.7| 20.1| 0.82| 0.44| 1.07|
March | 42.0| 23.6| 32.8| 1.89| 1.28| 2.42|
April | 58.2| 36.3| 47.2| 3.42| 2.36| 4.45|
May | 70.8| 47.7| 59.2| 3.82| 2.96| 4.96|
June | 79.7| 56.7| 68.2| 4.20| 2.80| 5.46|
July | 83.7| 61.4| 72.6| 3.99| 2.75| 5.19|
August | 81.5| 59.0| 70.3| 4.03| 2.55| 5.23|
September | 72.7| 50.7| 61.7| 3.93| 2.07| 5.11|
October | 61.0| 39.9| 50.5| 2.27| 1.37| 2.95|
November | 43.8| 27.0| 35.4| 1.68| 0.89| 2.18|
December | 28.3| 12.1| 20.2| 1.21| 0.78| 1.57|
----------|-----|-----|-----|-----|-----|-----|
----------|-----|-----|-----|-----|-----|-----|
Yearly : |-----|-----|-----|-----|-----|-----|
----------|-----|-----|-----|-----|-----|-----|
Average | 56.3| 35.9| 46.1| --- | --- | --- |
----------|-----|-----|-----|-----|-----|-----|
Extreme | 101| -39| --- | --- | --- | --- |
----------|-----|-----|-----|-----|-----|-----|
Total | --- | --- | --- |32.01|28.58|41.55|
----------|-----|-----|-----|-----|-----|-----|
----------------------------------------------|
GROWING SEASON DATES
WETS Station : DECORAH, 192110
Start yr. - 1971 End yr. - 2000
Requested years of data: 30 Available years of data: 30
Missing data years 24 deg = 1, 28 deg = 1, 32 deg = 1
Years with no occurrence 24 deg = 0, 28 deg = 0, 32 deg = 0
Data years used 24 deg = 29, 28 deg = 29, 32 deg = 29
------------------------------------------------------------------------
| Temperature
---------------------------|--------------------------------------------
Probability | 24F | 28F | 32F
---------------------------|--------------|--------------|--------------
| Growing Season Length
| Beginning and Ending Dates
|
5 years in 10 -- | 189 days | 161 days | 143 days
| 4/15 to 10/21 4/31 to 10/ 9 5/13 to 10/ 2
| | |
7 years in 10 -- | 197 days | 170 days | 151 days
| 4/ 9 to 10/23 4/24 to 10/12 5/ 6 to 10/ 4
| | |
------------------------------------------------------------------------
7 Climatic Data and Conservation Practices [TOC]
The following table provides recommendations on the most
appropriate climatic data to use in analysis of the practice for
application on a particular field. Values refer to the average or
normal values for a particular element and time interval but may
refer to a special type of analysis for that time interval ie.
probability.
The Practice Names are linked to the appropriate standard which can
be retrieved in pdf 
format by selecting the practice name.
M=monthly, D=daily, H=hourly, 15=15 minute, F=frequency, R=roses
prec = Precipitation, temp = Temperature Max & Min, evap =
Evaportation, wind = Wind Movement
This page last revised - November 18, 1998
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