Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective September 2012, the GHCN-M version 3.2.0 dataset of monthly mean temperature replaced the GHCN-M version 3.1.0 monthly mean temperature dataset. Beginning with the August 2012 Global monthly State of the Climate Report, released on September 17, 2012, GHCN-M version 3.2.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends. For more information about this newest version, please see the GHCN-M version 3.2.0 Technical Report.
*The GHCN-M version 3.1.0 Technical Report was revised on September 5, 2012 to accurately reflect the changes incorporated in that version. Previously that report incorrectly included discussion of changes to the Pairwise Homogeneity Algorithm (PHA). Changes to the PHA are included in version 3.2.0 and described in the version 3.2.0 Technical Report. Please see the Frequently Asked Questions to learn more about this update.
Global Highlights:
- Global average land and sea surface temperature was the second
warmest on record for both May and spring (March-May)
- For March-May, lower tropospheric temperatures remained
slightly above average, while stratospheric temperatures were
cooler than average
- Wettest areas during March-May were southeast Asia, southern
South America and parts of western Europe
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Contents of this Section:
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 Temperature
- Global average land and ocean temperature ranked
second warmest in May and was 0.51°C (0.92°F) above the
long-term average using a 1880-2000 base period (0.41°C /
0.74°F above the 1961-1990 mean
- Temperature averaged in the Northern
Hemisphere ranked second warmest and was 0.63°C
(1.13°F) above average
- The El Niño event of 1998 was associated
with the warmest May on record, with a global average land and
ocean temperature anomaly of 0.66°C (1.19°F)
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- For spring (March-May), the global average land
and ocean temperature was 0.57°C (1.03°F) above the
1880-2000 mean, or second warmest (0.43°C
/ 0.77°F above the 1961-1990 mean)
- Temperatures averaged over land surfaces were
also second warmest this spring, with a positive departure of
0.99°C (1.78°F) using the 1880-2000 mean
- The global ocean temperature for March-May
ranked second warmest or 0.39°C (0.70°F) above
average
- Southern
Hemisphere temperatures for March-May were third warmest, or
0.44°C (0.79°F) above average
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- May temperatures across extratropical land areas
of the Northern Hemisphere (90°N-20°N) were the warmest
on record in 2001 (1.18°C / 2.12°F above average)
exceeding the previous record set in May 2000 by 0.20°C
(0.36°F)
- Land areas in the tropics ranked third warmest
in May, or 0.82°C (1.48°F) above the 1880-2000 mean
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- Anomalous warmth dominated much of the Northern
Hemisphere during spring 2001, with the greatest departures in
eastern Canada, North Africa and much of Asia
- This temperature distribution was much the same
during the month of May
- Cooler than average temperatures with negative
anomalies of -2 to -4°C (-3.6 to -7.2°F) were observed
over Scandinavia and southern South America
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Precipitation
- Drier than average conditions during the
March-May period affected areas in northern South America and from
the Middle East into much of China
- Wet weather, with seasonal departures exceeding
twice the average, was located across parts of Argentina, southern
Asia and western Europe
- Unusually wet weather in May
was most evident over parts of North Africa, northwest India and
Indochina
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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.
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