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.
Temperature anomaly patterns changed significantly
during March from what they were in February. The cold water off
the west coast of South America warmed somewhat, although mature La
Niña conditions in the east equatorial Pacific are predicted
to remain for the next few months. There were warmer than average
temperatures in March in central Australia and east central South
America. The warm anomalies over the eastern U.S. during January
and February shifted to colder than average temperatures in March.
Conversely, the cold anomalies in February over Europe shifted to
above average temperatures. The extreme warmth in eastern China
abated somewhat, particularly near the coast. March did bring a
continuation of unusually warm temperatures to New Zealand,
northern Indochina, north central and southern Africa, the eastern
Mediterranean, eastern Canada and north central U.S. Cold anomalies
in western Australia and the east coast of Africa continued for the
second month in a row.
Mean monthly temperature anomalies for March (using a
base period 1880-1998) are shown in the figure below. Global
temperatures continued to be well above average in the month of
March. The average temperature over land and ocean was 0.54 C above
the long term mean (1880-1998). Although this was the 4th highest
March anomaly on record, the average temperature was 0.21 C less
than the average temperature for March 1998.
|This continues a trend
toward cooler temperature anomalies (but still above the long term
average) that began last year with the transition from El
Niño to La Niña conditions. In recent months, sea
surface temperature measurements showed the most significant
cooling. March land surface measurements indicate that significant
cooling is now occurring over land areas as well. March land
surface temperatures were 1.05 C above the long term mean, 0.21 C
less than the average for March 1998.
|This figure shows
widespread areas of above average land surface temperatures in
March 1999. Some of the largest positive anomalies occurred in
Canada and the northern U.S. where anomalies exceeded 5.0 C. The
average temperature for this region was
5.20 C above the long term mean, only 0.47 C less than the largest
anomaly on record for this region. Areas of the eastern U.S. that
had been above average in January and February experienced slightly
cooler than average temperatures in March.
Europe, which was only slightly warmer than usual in February,
recorded well above average temperatures in March. Anomalies were
greater than 4.0 C in Germany, Poland and northern regions of
Scandinavia. Above average temperatures also occurred throughout
India, China, the Far East, the Mediterranean and parts of Africa
and South America. The extremely warm temperatures throughout
Canada are a sharp contrast to the large region of cold anomalies
across Russia and Mongolia. Below normal temperatures recorded in
Siberia throughout the winter months spread south into Central
Russia and Mongolia in March as a low pressure trough extended its
influence into this region. Temperatures
averaged 4.4 C below the long term mean, the coldest since
1960. Alaska also continued a stretch of colder than average
months, with anomalies as much as 2.0 C below average.
|The persistance of the
temperature patterns over the past few months can be seen in this
figure of the anomalies for the 3-month period January through
March. Above average temperatures were widespread across almost all
of Canada and central United States during this period. Warmer than
average temperatures also stretched from Europe to the Far East.
Areas of below average temperatures can be seen in Alaska, Siberia
and southern areas of South America, with isolated areas of
slightly below average temperatures in other areas of the
|As shown in the
adjacent figure, global precipitation averaged more than 7.0 mm
(0.28 inches) above the long term mean (1900-1998) in March. This
was the 3rd month in a row with above normal precipitation.
Although the globally averaged anomaly was strongly positive, in
areas for which data were available, the following spatial
distribution plot of precipitation anomalies shows that there was a
nearly even distribution of positive and negative anomalies across
Areas along the eastern coast of China, that have been
experiencing drought conditions throughout the past several months,
received above average rainfall in March. However, much of China
remained drier than normal, exacerbating already dry conditions.
Rainfall was as much as 50 mm (2 inches) below average across a
large part of south central China. The dry conditions stretched
west into India and Pakistan where precipitation averaged 36.4 mm
(1.4 inches) below average.
|Many islands of the South
Pacific, that had been wetter than average through the first 2
months of the year, continued to receive above average rainfall in
March. Above average rainfall also fell across portions of
northeastern and western Australia. Precipitation was more than 100
mm (4 inches) above average in some coastal areas. Japan and North
and South Korea were also wetter than usual, averaging 23 mm (1
inch) above the long term mean for the month.
Drier than average conditions persisted across a large
portion of South America, while much of the southern half of the
continent was wetter than usual. Precipitation across Argentina
averaged 44 mm (1.7 inches) above average in March. Much of the
North American continent experienced drier than average conditions
in March. Some exceptions are areas of the United States
and a few isolated areas in Canada which received above average
Global Surface Wetness
|Surface wetness was
above average in portions of Europe, where excessive snow pack
melted away. It was wetter than average in areas of northwest and
southern Africa, central Argentina, and southern Australia. There
were also many areas with below average wetness in March, such as a
large portion of central China, the Ukraine, southern Russia, and
southern Africa, where a drought has persisted for months.
These past few months, the snow cover has persisted longer than
usual in the midwestern United States and western Russia. Water in
its frozen state is not detected as surface wetness, i.e., liquid
water, and therefore is indicated as a negative surface moisture
anomaly. Sizable areas in northeastern Argentina, the Mideast, and
northern Australia were drier than average this month.