National Climatic Data Center
15 August 2008
The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. The most current data may be accessed via the Global Surface Temperature Anomalies page.
Temperature anomalies for July 2008 are shown on the dot maps below. The dot map, below left, provides a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The dot map, below right, is a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.
During July, above average temperatures were observed across Japan, the British Isles, northwestern Africa, the northwestern and northeastern continental U.S., and most of South America, Europe, Australia, and Asia. Meanwhile, cooler-than-average conditions were present across far northwestern Europe, the southern and western coasts of Alaska, north-central Russia, parts of the north-central contiguous U.S., Mexico, and southeastern China.
Sea surface temperatures (SSTs) during July 2008 were warmer than average in the Atlantic, northwestern Pacific and eastern equatorial Pacific oceans, and parts of the Indian Ocean. Cooler-than-average SSTs were present in parts of the southern hemisphere and in the central equatorial Pacific Ocean.
Anomalously warm temperatures covered much of the world's land surface for the first seven months of the year. The January-July 2008 map shows the presence of warmer-than-average temperatures across all land areas, with the exception of parts of the northern continental U.S. and eastern Australia. Warmer-than-average SST conditions were present in the Atlantic and Indian oceans, eastern equatorial Pacific and parts of the northwest Pacific oceans. Cooler-than-average conditions were observed in the central equatorial Pacific, parts of the northeastern Pacific and some areas in the southern oceans.
The mean position of the upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the July map, respectively) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products, please see the Climate Monitoring Global Products page.
Images of sea surface temperature conditions are available for all weeks during 2008 at the weekly SST page.
Effective with the February 2006 report, NCDC transitioned from the use of the Operational Global Surface Temperature Index (Quayle et al. 1999) to the blended land and ocean dataset developed by Smith and Reynolds (2005). The differences between the two methods are discussed in Smith et al. (2005). The ranks found in the tables below are based on records that began in 1880.
The combined global land and ocean surface temperature tied with 2001 and 2003 as the fifth warmest July on record, while the January-July year-to-date was the ninth warmest on record.
| July | Anomaly | Rank (out of 129 years) |
Warmest (or Next Warmest) Year on Record |
|---|---|---|---|
GlobalLandOcean Land and Ocean |
+0.68°C (+1.22°F) +0.42°C (+0.76°F) +0.49°C (+0.88°F) |
5th warmest 8th warmest 5th warmest |
1998 (+0.99°C/1.78°F) 1998 (+0.55°C/0.99°F) 1998 (+0.67°C/1.21°F) |
Northern HemisphereLandOcean Land and Ocean |
+0.63°C (+1.13°F) +0.51°C (+0.92°F) +0.55°C (+0.99°F) |
7th warmest 6th warmest 7th warmest |
2002 (+1.02°C/184°F) 2005 (+0.64°C/1.15°F) 2005 (+0.76°C/1.37°F) |
Southern HemisphereLandOcean Land and Ocean |
+0.83°C (+1.49°F) +0.36°C (+0.65°F) +0.43°C (+0.77°F) |
4th warmest 11th warmest 6th warmest |
1998 (+0.91°C/1.64°F) 1998 (+0.57°C/1.03°F) 1998 (+0.62°C/1.12°F) |
| January-July | Anomaly | Rank (out of 129 years) |
Warmest (or Next Warmest) Year on Record |
|---|---|---|---|
GlobalLandOcean Land and Ocean |
+0.75°C (+1.35°F) +0.34°C (+0.61°F) +0.45°C (+0.81°F) |
6th warmest 10th warmest 9th warmest |
2007 (+1.07°C/1.93°F) 1998 (+0.53°C/0.95°F) 1998 (+0.64°C/1.15°F) |
Northern HemisphereLandOcean Land and Ocean |
+0.86°C (+1.55°F) +0.36°C (+0.65°F) +0.55°C (+0.99°F) |
6th warmest 8th warmest 7th warmest |
2007 (+1.27°C/2.29°F) 2005 (+0.53°C/0.95°F) 2007 (+0.75°C/1.35°F) |
Southern HemisphereLandOcean Land and Ocean |
+0.43°C (+0.77°F) +0.32°C (+0.58°F) +0.34°C (+0.61°F) |
13th warmest 19th warmest 17th warmest |
2005 (+0.91°C/1.64°F) 1998 (+0.56°C/1.01°F) 1998 (+0.60°C/1.08°F) |
The most current data may be accessed via the Global Surface Temperature Anomalies page.
The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. Precipitation during July 2008 was variable in many areas. Above average precipitation fell over areas that include the British Isles, northeastern Australia, central Russia, and parts of the eastern half of the continental U.S. and eastern Asia. Drier-than-average conditions were observed across Norway, the western and north-central contiguous U.S., southern Australia, and parts of South America and Asia.
According to the Australian Bureau of Meteorology (BoM), unseasonal rains fell across parts of eastern Queensland. As a whole, the State of Queensland had a monthly average of 95 percent above normal (BoM).
In the U.S., hurricane Dolly brought much needed rain to parts of the South, but at month's end, moderate to exceptional drought remained over 46 percent of the region. Typhoon Kalmaegi passed over the Philippines, Taiwan and eastern China, killing at least 18 people and causing about $10 million (U.S.) in damage. Some mountainous locations in Taiwan reported more than 1,100 mm (43 inches) of rain during the storm. A few days later, Typhoon Fung-Wong passed over many of the same areas, dumping 838 mm (32.9 inches) of rain on Hualien on Taiwan's east coast. Extensive damage exceeding $6 million (U.S.) and 6 fatalities were reported. Heavy monsoon rains impacted northern India and Bangladesh between July 5-14, resulting in floods and landslides that claimed 20 lives. Eleven people died in monsoon flooding and landslides in Nepal in early July.
Additional details on flooding and drought can also be found on the July Global Hazards page.
Sea surface temperatures (SST) warmed across the equatorial Pacific Ocean during July. Above or near average SST anomalies were present across all of the Niño regions. These conditions are indicative of a neutral ENSO phase (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of July 2008 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction Center (CPC) and the CPC ENSO Diagnostic Discussion.
Images of sea surface temperature conditions are available for all weeks since 2003 at the weekly SST page.
According to the National Snow and Ice Data Center, the July 2008 Northern Hemisphere sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was below the 1979-2000 mean. This was the fourth least July sea ice extent on record. The previous three years had the least July sea ice extent since records began in 1979, with 2007 having the least July sea ice extent (19.5 percent below the 1979-2000 mean) on record. Sea ice extent for July has decreased at a rate of 6.1 percent per decade (since satellite records began in 1979) as temperatures in the high latitude Northern Hemisphere have risen at a rate of approximately 0.37°C per decade over the same period.
Meanwhile, the July 2008 Southern Hemisphere sea ice extent was above the 1979-2000 mean. This was the tenth largest sea ice extent in July (1.2 percent above the 1979-2000 mean) over the 30-year historical period. Sea ice extent for July has increased at a rate of 0.7 percent per decade.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page, provided by the NOAA's National Snow and Ice Data center (NSIDC).
Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.
These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the UAH and RSS sources of troposphere data is available.
| July | Anomaly | Rank (out of 30 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.06°C/+0.11°F | 15th warmest | 1998 (+0.52°C/0.94°F) | +0.10°C/decade |
| *RSS low-trop | +0.15°C/0.27°F | 11th warmest | 1998 (+0.62°C/1.12°F) | +0.17°C/decade |
*Version 03_0
| January- July |
Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | -0.02°C/-0.04°F | 19th warmest (12th coolest) |
1998 (+0.62°C/+1.12°F) [1985 (-0.22°C/-0.40°F)] |
+0.12°C/decade |
| *RSS low-trop | +0.03°C/+0.05°F | 20th warmest | 1998 (+0.68°C/+1.22°F) | +0.17°C/decade |
*Version 03_0
These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 3-10 km (2-6 miles) above the Earth's surface), which also includes a portion of the lower stratosphere. (The MSU channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km (6 miles).) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.
The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.
Radiosonde measurements indicate that for the January-July year-to-date period, temperatures in the mid-troposphere were 0.13°C (0.23°F) above average, resulting in the 20th warmest January-July since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-July year-to-date period for the middle troposphere varied from fourth coolest (27th warmest) to tenth coolest (21st warmest) on record.
The global mid-troposphere temperatures were near average in July 2008. As shown in the table below, satellite measurement for July 2008 ranked from 13th warmest to 20th warmest on record.
| July | Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.07°C/-0.13°F | 20th warmest (11th coolest) |
1998 (+0.47°C/+0.85°F) [1985 (-0.35°C/-0.63°F)] |
+0.05°C/decade |
| *RSS mid-trop | +0.02°C/+0.04°F | 17th warmest | 1998 (+0.51°C/+0.92°F) | +0.11°C/decade |
| **UW-UAH mid-trop | +0.03°C/+0.05°F | 17th warmest | 1998 (+0.59°C/+1.06°F) | +0.11°C/decade |
| **UW-*RSS mid-trop | +0.12°C/0.22°F | 13th warmest | 1998 (+0.63°C/+1.13°F) | +0.17°C/decade |
*Version 03_0
| January- July |
Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.16°C/-0.29°F | 27th warmest (4th coolest) |
1998 (+0.57°C/+1.03°F) [1989 (-0.25°C/-0.45°F)] |
+0.04°C/decade |
| *RSS mid-trop | -0.10°C/-0.18°F | 24th warmest (7th coolest) |
1998 (+0.60°C/+1.08°F) [1989 (-0.23°C/-0.41°F)] |
+0.09°C/decade |
| **UW-UAH mid-trop | -0.07°C/-0.13°F | 22nd warmest (9th coolest) |
1998 (+0.70°C/+1.26°F) [1989 (-0.27°C/-0.49°F)] |
+0.10°C/decade |
| **UW-*RSS mid-trop | -0.01°C/-0.02°F | 21st warmest (10th coolest) |
1998 (+0.72°C/+1.30°F) [1989 (-0.24°C/-0.43°F)] |
+0.15°C/decade |
| RATPAC | +0.13°C/+0.23°F | 20th warmest (out of 51 years) |
1998 (+0.81°C/+1.46°F) | +0.14°C/decade |
*Version 03_0
The table below summarizes stratospheric conditions for July 2008. On average, the stratosphere is located approximately between 16-23 km (10-14 miles) above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.
| July | Anomaly | Rank (out of 30 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.59°C (-1.06°F) | 5th coolest | 1996 (-0.73°C/-1.31°F) |
| *RSS stratosphere | -0.49°C (-0.88°F) | 5th coolest | 1996 (-0.65°C/-1.17°F) |
*Version 03_0
For additional details on precipitation and temperatures in July, see the Global Hazards page.
Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology, 17, 1153-1170.
Free, M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.
Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.
Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.
Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224-240.
Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.
Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 tropospheric Temperature Record. J. Clim, 16, 3650-3664.
Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.
Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.
Smith, T.M., and R.W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.
For all climate questions, other than questions concerning this report, please contact the National Climatic Data center's Climate Services Division:
Climate Services DivisionFor questions about this report, please contact:
Ahira Sánchez-Lugo-or-
Climate Monitoring Branch
http://www.ncdc.noaa.gov/oa/climate/research/2008/jul/global.html 
