Our recently-ended March 2011 was a strange month with lots of temperature variability and some interesting precipitation events. From a temperature standpoint, the month was 5.6 degrees colder than last March and almost 1 degree colder than the thirty-year fixed normal (1971-2000). Our warmest day was that excellent 80-degree high temperature on March 18 and our coolest day was the 41-degree high on March 3 followed by the 42F just last week on March 31.
Precipitation was about 4.4” at National Airport, which is .8” above normal. The airport saw two days of trace snow accumulation (March 30th and 7th) with that little 0.2” dusting on March 27th.
This past month was a March of two minds as the first two-thirds of the period featured a broad, warm upper level ridge pattern over the Eastern U.S. That culminated with our 80-degree reading on March 18. Then the pattern shifted gears toward a blocking Greenland ridge feature for the final third. This re-directed substantial Canadian cold air supply right into our backyard to make for a miserable conclusion of wintertime blahs. Fortunately, that block is already breaking apart to allow us to sneak in some nicer days like Monday again!
Looking at March temperatures in a larger historical context, our 45.6F for the month is on the cooler side of the last few decades’ averages, but just slightly warmer than 2009’s March average of 45.2F.
The entire data set (dating back to the late 1800s) that includes a long stint at the downtown measurement site (prior to the 1942) shows that the two warmest Marches on record occurred in 1921 and 1945. Both of those years were 10 degrees warmer than this past March. The coldest Marches on record occcurred in 1885 and 1960 and were about 10 degrees colder than this past March.
The National Weather Service publishes nice monthly assessments usually within a week of the close of each month.
You can click on your closest airport location here:
Washington, DC data provided by NOAA and Speedwell Weather .