The U.S. National Oceanic and Atmospheric Administration (NOAA) released today (12 February 2010) data indicating that January 2010 was the fourth warmest on record.  Land surface temperatures were the highest on record in the Southern Hemisphere; and global ocean surface temperatures were the second warmest on record.

Global Highlights

Among the highlights (emphasis added):

• "The combined global land and ocean average surface temperature for January 2010 was 0.60°C (1.08°F) above the 20^th century average of 12.0°C (53.6°F). This is the fourth warmest January on record.
• The global land surface temperature for January 2010 was 0.83°C (1.49°F) above the 20^th century average of 2.8°C (37.0°F)—the twelfth warmest January on record. Land areas in the Southern Hemisphere were the warmest on record for January. In the Northern Hemisphere, which has much more land, comparatively, land surface temperatures were 18^th warmest on record.
• The worldwide ocean surface temperature for January 2010 was the second warmest—behind 1998—on record for January, 0.52°C (0.94°F) above the 20^th century average of 15.8°C (60.5°F). This can be partially attributed to the persistence of El Niño across the equatorial Pacific Ocean. According to NOAA's Climate Prediction Center (CPC), El Niño is expected to continue through the Northern Hemisphere spring 2010. "

NOAA: "As shown in the dot maps above, warmer-than-average temperatures during the month of January were present across much of the world's land areas. The warmest anomalies occurred in the high latitudes of the Northern Hemisphere, specifically in Canada, the western contiguous U.S., and parts of northern Russia. Cooler-than-average conditions were present across western Alaska, the southeastern contiguous U.S., northern Australia, and most of Europe and Russia."

As the figure below indicates, the high January temperatures were part of a clear long term trend for the planet as a whole and for the individual hemispheres. Relatively cool Januaries are indicated by blue bars and warm Januaries are in red.  The magnitude of the anomaly is reflected in the length of the bar.  Januaries are getting warmer, and every January for more than three decades has been anomalously warm for the Earth's surface as a whole.

Note that NASA soon will be releasing its data and will show similar though not identical rankings and trends.

U.S. Highlights

As the global map above indicated, there was a cool patch (indicated in blue) in January in the eastern U.S.  This is more clearly indicated below.  But many other states were either near normal or above normal.  Much above normal temperatures were recorded in Maine and the Pacific Northwest. 

Overall, national temperatures were slightly above average for the month, as the figure below indicates.   

Online Resources:

• State of the Climate, Global Analysis, January 2010
• State of the Climate, National Overview, January 2010