Our very warm March has come to a close and not only was it the warmest on record (since 1871), but it also extends our streak of above normal monthly temperature averages to 5 months in Washington, D.C.
The warm March pattern brought about an explosive start to spring. The D.C. cherry blossoms had their earliest peak (3/20) since March 2000 (3/17).
We experienced so many warm days (70s and 80s) and mild evenings (50s) that the average temperature was 10.0 degrees F above normal. The average temperature of 56.8F was 5.1F warmer (that’s a lot!) than the last top 10 warm March that occurred in 2000. Remarkably, 2012’s average March temperature was exactly the same as the 1981-2010 average April temperature in Washington, D.C.
Also, March 2012 was dry. At least it wasn’t bone dry like 2006’s super-small .05”, but our 1.02” tied for sixth-driest with 1947. That’s a deficit of 2.46” (March average is 3.48”).
March saw a wide variety of temperatures with highs ranges from the 40s to the 80s. Interestingly, Reagan National Airport only set one record high temperature for the entire month, which was the 82F back on March 15th. It did set four other record warm minimum temperatures on March 24 (54, tie), March 21 (59), March 20 (62), and March 19 (56). But you would think for such a record-breaking month, we would have seen more record-breaking temperatures. It was more about the persistence than the extremes, it seems.
Here is where we spent most of our highs and lows in March (70s and 50s):
Like much of this past winter, a very cold pattern dominated far western to northwestern Canada into Alaska, while a very warm ridging pattern in the jet stream dominated the central to eastern thirds of the U.S. The March pattern was the most amplified of the entire cold season (November-March), which easily allowed us to hit the new record warm monthly reading.
The main drivers for this very warm pattern were the negative Pacific Decadal Oscillation (PDO) and the Madden-Julian Oscillation (MJO). Both of these features, combined with lingering La Nina impacts, helped drive the warm and dry jet stream story.
There is a good chance that April could continue the warm monthly streak into a sixth month. The various guidance tools suggest that April will not be as warm as March relative to normal. Changes in blocking patterns, the Madden Julian Oscillation, and the La Nina suggest we could see more variability and less sustained big warm periods. Also, our normal temperatures are warming, which should limit the extremes of the March anomalies.
The National Weather Service publishes nice monthly assessments usually within a week of the close of each month (should be available shortly):
You can click on your closest airport location here:
Historical Washington, DC data provided by Speedwell Weather and NOAA. Also, check out Ian’s excellent rundown on March climatology.
CWG’s Jason Samenow contributed to this post.