Global Analysis - April 2009


Global Highlights

  • Based on preliminary data, the globally-averaged combined land and sea surface temperature was the fifth warmest on record for April, and the January-April year-to-date period tied with 2003 as the sixth warmest on record.
  • The greatest warm temperature anomalies during April 2009 occurred across Mexico, the northeastern U.S., southern South America, and most of Europe and Asia. Cooler-than-average temperatures occurred across north central to southeastern U.S. and western Asia.
  • Precipitation during April 2009 was above average across the Philippine Islands, the midwestern and central contiguous U.S., northeastern Brazil, eastern Australia, and parts of western Europe and southeastern Asia. Drier-than-average conditions were observed across much of South America, eastern Europe, and Alaska's panhandle.
  • The El Niño-Southern Oscillation (ENSO) transitioned from a cold phase (La Niña) to ENSO-neutral conditions during April 2009.

Contents of this Section:


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.


Introduction

Temperature anomalies for April 2009 are shown on the dot maps below. The dot map on the left provides 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 map on the right is 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.

During April 2009, warmer-than-average temperatures were present across Mexico, the northeastern and western contiguous U.S., eastern Canada, western Alaska, southern South America, northwestern Africa, and most of Europe, Asia, and Australia. In contrast, cooler-than-average temperatures occurred throughout western Asia and from the north central to the southeastern United States.

According to the Australian Bureau of Meteorology (BoM), southeastern Australia experienced a cold outbreak during the last week of the month, setting several record lows. Charlotte Pass set a new Australian minimum temperature record for the month of April as temperatures dropped to -13.0°C (8.6°F) on April 29, while Mount Hotham set a state record for Victoria when temperatures fell to -8.2°C (17.2°F). A complete April 2009 Australian Climate Summary is available, courtesy of the BoM.

Sea surface temperatures during April 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, the central Atlantic, and the high-latitude and southern oceans. Some warming took place across the equatorial Pacific Ocean, resulting in warmer sea surface temperature anomalies in all Niño regions during April 2009 with respect to March 2009 anomalies. These conditions are indicative of a transition from a cold phase ENSO (La Niña) to ENSO-neutral conditions. Please see the April 2009 ENSO discussion for additional information.

The January-April 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 Alaska, southern Canada, northern Australia, eastern Russia, and northwestern South America. Sea surface temperatures were warmer than average across the North Indian and western Pacific oceans, and parts 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 April 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.

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Temperature Rankings and Graphics

Current Month / Year-to-date

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.

April 2009 was the fifth warmest April since global surface records began in 1880 for combined global land and ocean surface temperatures. April land surface temperatures were fifth warmest, while ocean surface temperatures tied with 2003 as the fifth warmest in the 130-year record. The year-to-date (January-April) land and ocean combined temperature tied with 2003 as the sixth warmest on record.

April Anomaly Rank
(out of 130 years)
Warmest (or Next
Warmest) Year on Record

Global

Land
Ocean
Land and Ocean

+1.00°C (+1.80°F)
+0.44°C (+0.79°F)
+0.59°C (+1.06°F)

5thwarmest
5th warmest
5th warmest

2007 (+1.46°C/2.63°F)
1998 (+0.53°C/0.95°F)
1998 (+0.70°C/1.26°F)

Northern Hemisphere

Land
Ocean
Land and Ocean


+1.06°C (+1.91°F)
+0.38°C (+0.68°F)
+0.64°C (+1.15°F)


5th warmest
8th warmest
5th warmest


2000 (+1.72°C/3.10°F)
2004 (+0.53°C/0.95°F)
2007 (+0.87°C/1.57°F)

Southern Hemisphere

Land
Ocean
Land and Ocean


+0.78°C (+1.40°F)
+0.49°C (+0.88°F)
+0.53°C (+0.95°F)


7th warmest
2nd warmest
4th warmest


2005 (+1.13°C/2.03°F)
1998 (+0.59°C/1.06°F)
1998 (+0.63°C/1.13°F)
January-
April
Anomaly Rank
(out of 130 years)
Warmest (or Next
Warmest) Year on Record

Global

Land
Ocean
Land and Ocean

+0.92°C (+1.66°F)
+0.40°C (+0.72°F)
+0.54°C (+0.97°F)

8th warmest
7th warmest
6th warmest

2007 (+1.37°C/2.47°F)
1998 (+0.53°C/0.95°F)
2007 (+0.69°C/1.24°F)

Northern Hemisphere

Land
Ocean
Land and Ocean


+1.00°C (+1.80°F)
+0.34°C (+0.61°F)
+0.59°C (+1.06°F)


9th warmest
7th warmest
7th warmest


2007 (+1.55°C/2.79°F)
2004 (+0.50°C/0.90°F)
2007 (+0.87°C/1.57°F)

Southern Hemisphere

Land
Ocean
Land and Ocean


+0.65°C (+1.17°F)
+0.46°C (+0.83°F)
+0.48°C (+0.86°F)


5th warmest
5th warmest
6th warmest


2005 (+0.91°C/1.64°F)
1998 (+0.57°C/1.03°F)
1998 (+0.61°C/1.10°F)

The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Precipitation

The maps below represent anomaly values based on the GHCN dataset of land surface stations using a base period of 1961-1990. Precipitation during April 2009 was highly variable. Above-average precipitation fell over eastern Australia, northeastern Brazil, western Europe, the midwestern and central U.S., and parts of southeastern Asia. The areas with the driest anomalies included much of South America, eastern Europe, Alaska's panhandle, and parts of eastern Asia.

During April 2009, heavy rain prompted devastating floods and mudslides that affected over 300,000 people and caused 38 fatalities in northeastern Brazil. The region experienced its worst deluge in more than 20 years.

Torrential downpours across Zambia and Namibia wreaked havoc across the region as rivers burst over their banks, flooding homes and cropland. The floods affected nearly 700,000 people in Zambia and 344,000 in Namibia.

Additional details on flooding and drought can also be found on the April 2009 Global Hazards page.

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ENSO SST Analysis

As shown in the adjacent animation, sea surface temperatures (SST) warmed across the equatorial Pacific during April 2009, resulting in warmer anomalies in all Niño regions when compared to March 2009 anomalies. The Oceanic Niño Index [three-month (February-March-April) running average] was -0.5°C (-0.9°F), which equals the threshold of -0.5°C (-0.9°F). A comprehensive summary of April 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.

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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.

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.

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Citing This Report

NOAA National Climatic Data Center, State of the Climate: Global Analysis for April 2009, published online May 2009, retrieved on October 22, 2014 from http://www.ncdc.noaa.gov/sotc/global/2009/4.