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Climate of 2005 - May in Historical Perspective


Including Boreal Spring


National Climatic Data Center
14 June 2005
Global Analysis / Global Hazards / United States / U.S. Drought / Extremes
Use these links to access detailed analyses of Global and U.S. data.

Global Highlights:

  • Based on preliminary data, global averaged combined land and sea surface temperatures for both March-May 2005 and May 2005 were 2nd warmest on record.
  • March-May temperatures were above average over Alaska, Canada, the majority of Africa and Australia. Colder-than-average conditions occurred primarily in the eastern U.S., central Mexico and the Baltic area of Europe.
  • Precipitation during March-May was above average over the U.S. Pacific Northwest, western Europe, the Caribbean and parts of South America, with drier than average conditions over the U.S. central Great Plains, the majority of Australia, southeastern Asia and the Iberian Peninsula.
  • ENSO transitioned to a neutral phase as sea surface temperatures (SSTs) were slightly above normal across the central and western equatorial Pacific during May

Contents of this Section:
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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.
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Top of Page Introduction

Temperature anomalies for March-May and May 2005 are shown on the two maps below. These dot maps use anomalies that were calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. During the boreal spring, above average temperatures occurred over Alaska, Canada, Venezuela, Russia, the western half of the U.S., the majority of Africa, southeastern Asia and most of Australia. Cooler than average temperatures were observed over the eastern seaboard of the U.S., central Mexico, Finland, western Mongolia and parts of Japan. Despite a brief heat wave that occurred in India during the week of May 17th, central areas of India had cold anomalies for the season.

During May 2005, there were above average temperatures over Russia, Algeria, Brazil, Alaska, Canada, the western half of Australia, the majority of southeastern Asia, much of Europe, and the U.S. West Coast. Cooler than average temperatures were observed over Japan, Scandinavia, far eastern Australia, parts of India, the majority of the eastern half of the U.S., and portions of Mexico.

Current Seasonal Temperature Dot map
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Current month's Temperature Dot map
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The map below is a weekly product based on data from the Comprehensive Ocean-Atmosphere Data Set (COADS) of SST data. During May 2005, slightly warmer than average conditions occurred over large parts of the western and central Pacific, reflecting a transition from El Ni�o conditions to a neutral ENSO phase. SSTs were also warmer than average in much of the northern Pacific and northern Atlantic. Cooler than average SSTs were observed off the eastern coast of the U.S., the western coast of Ecuador and Peru, as well as in the Gulf of Guinea southward along the coast of Africa to Angola.
Current Month's SST map
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The mean position of upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500 millibar height anomalies on the May 2005 and the March-May 2005 maps) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all months during 2005 at the weekly SST page

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Top of Page Temperature Rankings and Graphics

Current Month / Seasonal / Year-to-date
May Anomaly Rank Warmest Year on Record
Global
Land
Ocean
Land and Ocean 		+0.80°C (+1.44°F)
+0.43°C (+0.77°F)
+0.54°C (+0.97°F)		 4th warmest
2nd warmest
2nd warmest		 1998 (+0.93°C/1.67°F)
1998 (+0.53°C/0.95°F)
1998 (+0.65°C/1.17°F)
Northern Hemisphere
Land
Ocean
Land and Ocean 		+0.82°C (+1.48°F)
+0.53°C (+0.95°F)
+0.65°C (+1.17°F) 		4th warmest
1st warmest
2nd warmest 		2001 (+0.98°C/1.76°F)
2nd - 1998 (+0.51°C/0.92°F)
1998 (+0.66°C/1.19°F)
Southern Hemisphere
Land
Ocean
Land and Ocean 		+0.74°C (+1.33°F)
+0.38°C (+0.68°F)
+0.45°C (+0.81°F) 		4th warmest
5th warmest
4th warmest		 2002 (+0.98°C/1.76°F)
1998 (+0.56°C/1.01°F)
1998 (+0.64°C/1.15°F)

Global Land and Ocean Triad plot
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Global Hemisphere Triad plot
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March-May Anomaly Rank Warmest Year on Record
Global
Land
Ocean
Land and Ocean 		+1.07°C (+1.93°F)
+0.42°C (+0.76°F)
+0.62°C (+1.12°F)		 3rd warmest
2nd warmest
2nd warmest		 2002 (+1.10°C/1.20°F)
1998 (+0.51°C/0.92°F)
1998 (+0.68°C/1.22°F)
Northern Hemisphere
Land
Ocean
Land and Ocean 		+1.08°C (+1.94°F)
+0.48°C (+0.86°F)
+0.72°C (+1.30°F) 		4th warmest
2nd warmest
tied for warmest 		2000 (+1.17°C/2.11°F)
1998 (+0.49°C/0.88°F)
1998 (+0.72°C/+1.30°F)
Southern Hemisphere
Land
Ocean
Land and Ocean 		+0.87°C (+1.57°F)
+0.40°C (+0.72°F)
+0.49°C (+0.88°F) 		3rd warmest
5th warmest
3rd warmest		 1998 (+1.03°C/1.85°F)
1998 (+0.53°C/0.95°F)
1998 (+0.63°C/1.13°F)

Global Land and Ocean Triad plot
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Global Hemisphere Triad plot
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January-May Anomaly Rank Warmest Year on Record
Global
Land
Ocean
Land and Ocean 		+0.92°C (+1.66°F)
+0.43°C (+0.77°F)
+0.58°C (+1.04°F)		 4th warmest
2nd warmest
3rd warmest		 2002 (+1.24°C/2.23°F)
1998 (+0.52°C/0.94°F)
1998 (+0.71°C/1.30°F)
Northern Hemisphere
Land
Ocean
Land and Ocean 		+0.90°C (+1.62°F)
+0.48°C (+0.86°F)
+0.65°C (+1.17°F) 		9th warmest
2nd warmest
4th warmest 		2002 (+1.40°C/2.52°F)
1998 (+0.51°C/0.92°F)
1998 (+0.79°C/1.42°F)
Southern Hemisphere
Land
Ocean
Land and Ocean 		+0.82°C (+1.48°F)
+0.42°C (+0.76°F)
+0.50°C (+0.90°F) 		2nd warmest
5th warmest
3rd warmest		 1998 (+0.89°C/1.60°F)
1998 (+0.54°C/0.97°F)
1998 (+0.61°C/1.10°F)

Global Land and Ocean Triad plot
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Global Hemisphere Triad plot
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The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Top of Page Precipitation

The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. During the 2005 boreal spring, above average precipitation fell over the the Caribbean, northwestern, northeastern and southeastern portions of the U.S., southern Brazil and Uruguay, the western coast of Australia, western Europe and far eastern Europe. Below average precipitation was observed along the Gulf of Alaska, the U.S. central Great Plains and middle Mississippi Valley, Peru, parts of Argentina, the majority of Australia, the Philippines and most of southeastern Asia.

During May 2005, above average precipitation fell over the the Caribbean, Uruguay, Malaysia, Scandinavia, northwestern U.S., and the eastern coast of China, while below average precipitation was observed in the eastern U.S., Peru, and most of India.

Current Season's Precipitation Dot map in Millimeters
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Current Month's Precipitation Dot map in Millimeters
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Top of Page ENSO SST Analysis




Last week of the month's ENSO condtions Map
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  • SSTs decreased in the eastern equatorial Pacific during May, indicating that ENSO is transitioning from a weak warm phase (El Ni�o) to neutral conditions (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of May 2005 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 each week during 2005 at the weekly SST page

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Top of Page Troposphere

Current Month / Seasonal
The table below summarizes mid-tropospheric conditions for May 2005. These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 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 6 miles).

Analysis of the satellite record that began in 1979 indicates that global temperatures are increasing in the mid-troposphere, but the magnitude of the trend differs based on the analysis methods used in adjusting for factors such as orbital decay and inter-satellite differences.

Scientists at the University of Washington {UW}, developed a method for quantifying the stratospheric contribution to the satellite record of tropospheric temperatures and applied an adjustment to the UAH and RSS temperature record that attempts to remove the satellite contribution (cooling influence) from the middle troposphere record. This method results in trends that are larger than the those from the respective source.

The UW-UAH adjusted data indicate that May 2005 was 7th warmest. The RSS data and the UW-RSS adjusted data indicate that May 2005 was the 7th and 5th warmest, respectively. For the boreal spring, RSS data indicate 5th warmest while the UW-RSS and UW-UAH adjusted data indicate 4th warmest, since records began in 1979.


May Anomaly Rank Warmest Year on Record Trend
*RSS mid-trop +0.22°C/0.40°F 7th warmest 1998 (+0.64°C/1.15°F) +0.13°C/decade
**UW-UAH mid-trop +0.16°C/0.29°F 7th warmest 1998 (+0.72°C/1.30°F) +0.10°C/decade
**UW-*RSS mid-trop +0.30°C/0.54°F 5th warmest 1998 (+0.75°C/1.35°F) +0.19°C/decade
*Version 02_1
RSS mid-trop image
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UW-UAH mid-trop image
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UW-RSS mid-trop image
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March-May Anomaly Rank Warmest Year on RecordTrend
*RSS mid-troposphere +0.29°C/0.52°F 5th warmest 1998 (+0.65°C/1.17°F) +0.13°C/decade
**UW-UAH mid-troposphere +0.26°C/0.47°F 4th warmest 1998 (+0.73°C/1.31°F) +0.10°C/decade
**UW-*RSS mid-troposphere +0.38°C/0.68°F 4th warmest 1998 (+0.77°C/1.40°F) +0.19°C/decade
*Version 02_1


RSS mid-trop image
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UW-UAH mid-trop image
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UW-RSS mid-trop image
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Mid-tropospheric and lower stratospheric temperature data are collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases 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 the University of Washington.

**An adjustment on both the RSS and UAH datasets provided by Fu et al. (2004) (University of Washington) is accomplished by deriving separate weighting coefficients for the MSU T2 and T4 over the tropics (30N to 30S), northern and southern hemispheres, and for the global mean by fitting radiosonde troposphere anomalies to radiosonde-simulated T2 and T4 anomalies over the period from 1958-2004 as

T850-300 = a0 + a2*T2 + a4*T4

where T850-300 is the radiosonde 850-300 hPa layer; T2 and T4 are the radiosonde simulated MSU brightness temperature anomalies; and a0, a2, and a4 are the coefficients derived from this linear regression.

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Top of Page Stratosphere

Current Month / Seasonal
The table below summarizes stratospheric conditions for May and March-May 2005. The stratosphere is located between 10-14 miles above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in large part due to the depletion of ozone. The large increase in temperature in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the increase in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. Therefore the base period used is 1984-1990 which was chosen to avoid contamination by these eruptions.


May Anomaly Rank Warmest Year on Record
UAH stratosphere -0.57°C (-1.03°F) 3rd coolest 1992 (+0.75°C/1.35°F)
*RSS stratosphere -0.41°C (-0.74°F) 4th coolest 1992 (+0.76°C/1.37°F)
*Version 02_1
UAH lower-strat image
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RSS lower-strat image
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March-May Anomaly Rank Warmest Year on Record
UAH stratosphere -0.46°C (-0.83°F) 3rd coolest 1983 (+0.92°C/1.66°F)
*RSS stratosphere -0.42°C (-0.76°F) 4th coolest 1992 (+0.85°C/1.53°F)
*Version 02_1


UAH lower-strat image
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RSS lower-strat image
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Mid-tropospheric and lower stratospheric temperature data are collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases 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 the University of Washington.

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For additional details on precipitation and temperatures in May, see the Global Hazards page .
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Top of Page References

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.
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For questions about this report, please contact:

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NOAA/National Climatic Data Center
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NOAA/National Climatic Data Center
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email: David.Easterling@noaa.gov
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