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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.
Please Note: Beginning with the July 2009 State of the Climate Report, NCDC will switch to a new version (version 3b) of the extended reconstructed sea surface temperature (ERSST) dataset. ERSST.v3b is an improved extended SST reconstruction over version 2. Most of the improvements are justified by testing with simulated data. The primary difference in version 3b, compared to version 2, is improved low-frequency tuning that increases the sensitivity to data prior to 1930. In ERSST v3b, satellite data was removed from the ERSST product. The addition of satellite data from 1985 to present caused problems for many users. Although the satellite data were corrected with respect to the in situ data, a small residual cold bias remained at high southern latitudes where in situ data were sparse. For more information about the differences between ERSST.v3b and ERSST.v2 please read Summary of Recent Changes in the Land-Ocean Temperature Analyses and Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006) paper.
Temperature anomalies for May 2009 and March-May 2009 are shown on the dot maps below. The dot maps on the left provide a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) dataset of land surface stations using a 1961-1990 base period. The dot maps on the right are a product of a merged land surface and sea surface temperature (SST) anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 average for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.
The May 2009 map shows warmer-than-average temperatures across much of the world's land areas, with the most anomalous warmth over Alaska, Iceland, the western contiguous U.S., and much of Europe and Asia. Meanwhile, cooler-than-average conditions were present across New Zealand, Canada, and parts of western and central Asia and Australia. Temperatures were 2-5°C (4-9°F) below the 1961-1990 average across large areas in Canada. According to Environment Canada, some locations across Ontario, Canada had their coolest mean temperature since 2002; meanwhile, the town of Kapuskasing had its coolest mean temperature since 1997 (Source: Environment Canada).
Sea surface temperatures during May 2009 were warmer than average across much of the world's oceans, with the exception of cooler-than-average conditions across parts of the northeastern Pacific, and parts of the northern and central Atlantic and Southern oceans. SST anomalies in all Niño regions continued to warm during May 2009, indicating persistence of ENSO-neutral conditions. Please see the May 2009 ENSO discussion for additional information.
During the boreal spring (March-May), temperatures were above average in Mexico, Europe, southern South America, northwestern Alaska, northwestern and southern Africa, and most of the contiguous U.S., Asia, and parts of Australia. Cooler-than-average temperatures were present across the Hawaiian Islands, Canada, and parts of the north central and northwestern United States.
The January-May 2009 map of temperature anomalies shows the presence of warmer-than-average conditions across much of the world's land areas, with the exception of cooler-than-average temperatures across parts of northeastern Australia, eastern Siberia, southern Alaska, north central contiguous U.S., and most of Canada. Sea surface temperatures were warmer than average across the North Indian and western Pacific oceans, and most of the Atlantic Ocean. Cooler-than-average SSTs were present across the equatorial Pacific Ocean, along the western coasts of North America and northwestern Africa, and across most of the southern oceans.
The average 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 March-May 2009 map and May 2009 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 2009 from the weekly SST page.
Current Month / Seasonal / Year-to-date
The combined global land and ocean surface temperature was the fourth warmest on record in May and the fifth warmest on record for boreal spring (March-May). The year-to-date (January-May) land and ocean combined temperature tied with 2003 as the sixth warmest on record. The ranks found in the tables below are based on records that began in 1880.
| May | Anomaly | Rank (out of 130 years) |
Warmest Year on Record |
|---|---|---|---|
| Global | |||
| Land | +0.66°C (+1.19°F) | 8th warmest | 2005 (+0.94°C/1.69°F) |
| Ocean | +0.48°C (+0.86°F) | 3rd warmest | 1998 (+0.54°C/0.97°F) |
| Land and Ocean | +0.53°C (+0.95°F) | 4th warmest | 1998 (+0.62°C/1.12°F) |
| Northern Hemisphere | |||
| Land | +0.66°C (+1.19°F) | 9th warmest | 2001 (+1.16°C/2.09°F) |
| Ocean | +0.44°C (+0.79°F) | 7th warmest | 2005 (+0.60°C/1.08°F) |
| Land and Ocean | +0.52°C (+0.94°F) | 9th warmest | 2005 (+0.73°C/1.31°F) |
| Southern Hemisphere | |||
| Land | +0.65°C (+1.17°F) | 7th warmest | 2002 (+1.03°C/1.85°F) |
| Ocean | +0.52°C (+0.94°F) | 2nd warmest | 1998 (+0.58°C/1.04°F) |
| Land and Ocean | +0.54°C (+0.97°F) | 3rd warmest | 1998 (+0.61°C/1.10°F) |
| March - May | Anomaly | Rank (out of 130 years) |
Warmest Year on Record |
|---|---|---|---|
| Global | |||
| Land | +0.87°C (+1.57°F) | 9th warmest | 2007 (+1.16°C/2.09°F) |
| Ocean | +0.44°C (+0.79°F) | 5th warmest | 1998 (+0.53°C/0.95°F) |
| Land and Ocean | +0.56°C (+1.01°F) | 5th warmest | 2005 (+0.65°C/1.17°F) |
| Northern Hemisphere | |||
| Land | +0.91°C (+1.64°F) | 9th warmest | 2000 (+1.37°C/2.47°F) |
| Ocean | +0.38°C (+0.68°F) | 8th warmest | 2005 (+0.52°C/0.94°F) |
| Land and Ocean | +0.58°C (+1.04°F) | 11st warmest | 2005 (+0.77°C/1.39°F) |
| Southern Hemisphere | |||
| Land | +0.76°C (+1.37°F) | 4th warmest | 2005 (+0.99°C/1.78°F) |
| Ocean | +0.49°C (+0.88°F) | 3rd warmest | 1998 (+0.57°C/1.03°F) |
| Land and Ocean | +0.53°C (+0.95°F) | 3rd warmest | 1998 (+0.62°C/1.12°F) |
| January - May | Anomaly | Rank (out of 130 years) |
Warmest Year on Record |
|---|---|---|---|
| Global | |||
| Land | +0.90°C (+1.62°F) | 6th warmest | 2007 (+1.27°C/2.29°F) |
| Ocean | +0.42°C (+0.76°F) | 7th warmest | 1998 (+0.53°C/0.95°F) |
| Land and Ocean | +0.54°C (+0.97°F) | 6th warmest | 2007 (+0.65°C/1.17°F) |
| Northern Hemisphere | |||
| Land | +0.96°C (+1.73°F) | 7th warmest | 2007 (+1.46°C/2.63°F) |
| Ocean | +0.36°C (+0.65°F) | 7th warmest | 1998 (+0.50°C/0.90°F) |
| Land and Ocean | +0.58°C (+1.04°F) | 7th warmest | 2007 (+0.83°C/1.49°F) |
| Southern Hemisphere | |||
| Land | +0.69°C (+1.24°F) | 4th warmest | 2005 (+0.91°C/1.64°F) |
| Ocean | +0.47°C (+0.85°F) | 4th warmest | 1998 (+0.57°C/1.03°F) |
| Land and Ocean | +0.50°C (+0.90°F) | 5th warmest | 1998 (+0.61°C/1.10°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 dataset of land surface stations using a base period of 1961-1990. The areas with the wettest anomalies during boreal spring included the eastern half of the contiguous U.S., northeastern Brazil, and southeastern Asia. The areas with the driest anomalies during March-May 2009 included South Africa, Alaska's panhandle, parts of northeastern and southern South America, eastern Asia, and most of Australia.
During May 2009, above-average precipitation fell over areas that included southeastern Asia, the southeastern contiguous U.S., northeastern Brazil, east central Australia, and parts of Russia, northern Europe, and northern India. Drier-than-average conditions were present across the Hawaiian Islands, Alaska's panhandle, the central U.S., northeastern South America, southern Europe, eastern Asia, and most of Australia.
Notable precipitation extremes during May 2009 include the heavy rain brought by typhoons Kujira and Chan-hom to parts of the Philippine Islands, prompting widespread floods and landslides. Torrential rain during the week of May 17 produced floods that claimed the lives of 11 people across Haiti. In Piaui, Brazil, heavy downpours caused a dam to rupture on May 28, inundating 120 homes and killing four people. In eastern Australia, a major storm brought heavy rain that caused significant floods in the region, forcing residents to flee the affected area. According to Australia's Bureau of Meteorology (BoM), the town of Dorrigo, New South Wales, received a total of 934 mm (37 inches) of precipitation during May 2009, including 409 mm (16 inches) that fell on May 22—the now second highest daily rainfall on record for the month of May in New South Wales (BoM).
Additional details on flooding and drought can also be found on the May 2009 Global Hazards page.
As shown in the adjacent animation, SST warmed across the equatorial Pacific during May 2009, resulting in warmer anomalies in all Niño regions when compared to April 2009 anomalies. The Oceanic Niño Index (three-month [March-April-May] running average) was -0.1°C (-0.2°F), which is above the threshold of -0.5°C (-0.9°F), indicating ENSO-neutral conditions. A comprehensive summary of May 2009 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions, please visit 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.
As shown in the time series to the right, the Northern Hemisphere snow cover extent during May 2009 was 1.9 million square kilometers below average, the seventh-lowest May snow cover extent on record. The 43-year average Northern Hemisphere May snow cover extent for the 1967-2009 period of record is 20.2 million square kilometers. Snow cover extent during spring 2009 was the sixth-lowest spring snow cover extent on record. The 43-year average Northern Hemisphere spring snow cover extent for the 1967-2009 period of record is 30.8 million square kilometers.
Across North America, snow cover for May 2009 was 0.2 million square kilometers below average, the 20th lowest May extent since satellite records began in 1967. Pickle Lake, Ontario, Canada set a new all-time May snowfall record when a total of 54.2 cm (21.3 inches) of snow fell during the month, surpassing the previous record of 49.6 cm (19.5 inches) set in 2002 (Source: Environment Canada). The average North America May snow cover extent is 9.6 million square kilometers for the 43-year period of record. Across North America, snow cover for spring 2009 was the 17th largest extent since satellite records began in 1967. The average North America spring snow cover extent is 12.9 million square kilometers for the 43-year period of record.
As depicted in the time series to the right, Eurasia's snow cover extent during May 2009 was 1.6 million square kilometers below average, the sixth-lowest snow cover extent on record. The 43-year average Eurasian snow cover extent in May is 10.6 million square kilometers for the 1967-2009 period of record. Eurasia's snow cover extent during spring 2009 was the fifth-lowest snow cover extent on record. The 43-year average Eurasian snow cover extent in spring is 17.9 million square kilometers for the 1967-2009 period of record.
Analysis provided by the Global Snow Laboratory, Rutgers University.
According to the National Snow and Ice Data Center, the May 2009 Northern Hemisphere sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was below the 1979-2000 average. This was the 15th lowest May sea ice extent on record, 1.6 percent below the 1979-2000 average. May Arctic sea ice extent has decreased at an average rate of 2.5 percent per decade since 1979.
Meanwhile, the May 2009 Southern Hemisphere sea ice extent was 6.6 percent above the 1979-2000 average. This was the fifth largest sea ice extent in May. Southern Hemisphere sea ice extent for May has increased at an average rate of 2.1 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 date back to 1979.
Current Month / Seasonal / Year-to-date
These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS) sources of troposphere data is available.
| May | Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.05°C/+0.09°F | 15th warmest | 1998 (+0.65°C/+1.17°F) | +0.06°C/decade |
| *RSS low-trop | +0.09°C/+0.16°F | 16th warmest | 1998 (+0.67°C/+1.20°F) | +0.13°C/decade |
*Version 03_0
| March -May |
Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.12°C/+0.21°F | 12th warmest | 1998 (+0.65°C/+1.16°F) | +0.10s°C/decade |
| *RSS low-trop | +0.16°C/+0.29°F | 12th warmest | 1998 (+0.70°C/+1.27°F) | +0.15°C/decade |
*Version 03_0
| January- May |
Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.20°C/+0.36°F | 8th warmest | 1998 (+0.66°C/+1.19°F) | +0.13°C/decade |
| *RSS low-trop | +0.21°C/+0.38°F | 8th warmest | 1998 (+0.68°C/+1.22°F) | +0.15°C/decade |
*Version 03_0
Current Month / Seasonal / Year-to-date
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 Microwave Sounding Unit [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-May year-to-date period, temperatures in the mid-troposphere were 0.39°C (0.70°F) above average, resulting in the eighth warmest January-May (out of 52 years) since global radiosonde measurements began in 1958. However, as shown in the table below, satellite analyses of the January-May year-to-date period for the middle troposphere varied from 11th to 16th warmest in the 31-year satellite record.
Similar to January-May year-to-date, radiosonde measurements indicate that temperatures were 0.34°C (0.62°F) above average during the boreal spring, giving March-May a rank of 12th warmest on record. The table below shows that satellite measurements for the boreal spring varied from 15th to 18th warmest on record.
The global mid-troposphere temperatures were near average in May 2009. As shown in the table below, satellite measurement for May 2009 ranked from 17th warmest to 20th warmest on record.
| May | Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.09°C/-0.16°F | 20th warmest | 1998 (+0.60°C/+1.08°F) | +0.00°C/decade |
| *RSS mid-trop | -0.03°C/-0.05°F | 18th warmest | 1998 (+0.64°C/+1.15°F) | +0.06°C/decade |
| **UW-UAH mid-trop | +0.01°C/+0.02°F | 18th warmest | 1998 (+0.77°C/+1.38°F) | +0.06°C/decade |
| **UW-*RSS mid-trop | +0.02°C/+0.04°F | 17th warmest | 1998 (+0.75°C/+1.36°F) | +0.11°C/decade |
*Version 03_0
| March- May |
Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.03°C/-0.06°F | 18th warmest | 1998 (+0.60°C/+1.07°F) | +0.01°C/decade |
| *RSS mid-trop | +0.02°C/+0.04°F | 16th warmest | 1998 (+0.64°C/+1.15°F) | +0.07°C/decade |
| **UW-UAH mid-trop | +0.06°C/+0.11°F | 15th warmest | 1998 (+0.74°C/+1.33°F) | +0.08°C/decade |
| **UW-*RSS mid-trop | +0.10°C/+0.18°F | 16th warmest | 1998 (+0.76°C/+1.37°F) | +0.13°C/decade |
| RATPAC | +0.34°C/+0.62°F | 12th warmest | 1998 (+0.87°C/+1.56°F) | +0.14°C/decade |
*Version 03_0
Note: RATPAC's rank is based on records that began in 1958 (52 years).
| January- May |
Anomaly | Rank (out of 31 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | +0.02°C/+0.04°F | 16th warmest | 1998 (+0.59°C/+1.06°F) | +0.03°C/decade |
| *RSS mid-trop | +0.06°C/+0.11°F | 14th warmest | 1998 (+0.63°C/+1.13°F) | +0.08°C/decade |
| **UW-UAH mid-trop | +0.13°C/+0.23°F | 11th warmest | 1998 (+0.73°C/+1.31°F) | +0.10°C/decade |
| **UW-*RSS mid-trop | +0.16°C/+0.29°F | 11th warmest | 1998 (+0.75°C/+1.35°F) | +0.14°C/decade |
| RATPAC | +0.39°C/+0.70°F | 8th warmest | 1998 (+0.80°C/+1.44°F) | +0.14°C/decade |
*Version 03_0
Note: RATPAC's rank is based on records that began in 1958 (52 years).
The table below summarizes stratospheric conditions for May 2009. On average, the stratosphere is located approximately 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.
| May | Anomaly | Rank (out of 31 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.39°C (-0.70°F) | 11th coolest | 2008 (-0.632°C/-1.13°F) |
| *RSS stratosphere | -0.29°C (-0.53°F) | 10th coolest | 1996 (-0.54°C/-0.97°F) |
*Version 03_0
| March- May |
Anomaly | Rank (out of 31 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.45°C (-0.81°F) | 9th coolest | 1999 (-0.63°C/-1.13°F) |
| *RSS stratosphere | -0.41°C (-0.74°F) | 8th coolest | 1999 (-0.60°C/-1.08°F) |
*Version 03_0
For additional details on precipitation and temperatures in May, 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 questions on technical or scientific content of this report, please contact:
Ahira Sánchez-Lugo:For general climate monitoring questions, please contact:
CMB.Contact@noaa.govFor climate data orders, please contact the National Climatic Data Center's Climate Services and Monitoring Division:
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