November 2012 for Washington, DC can best be described as a notably cool and dry month. The cool difference from average of -3 degrees Fahrenheit vs. the 30-year normal (1981-2010) was the first below normal temperature month of 2012 and the first since October 2011’s cool result. While it ties for the coolest November of the 2000s (see below), it is way down the list in the long-term history.

From a precipitation perspective, the measly 0.6” we saw at Washington Reagan National (DCA) tied for sixth driest on record and second driest of the 2000s (after a marginally drier 2001).

Below are the rankings for temperature in the 2000s and daily temperatures compared to average. We saw nearly three times as many cool days as warm days in November. November’s warmest temperature was 72F back on November 12th with the coldest reading being just last Thursday morning with 31F.

(Left) Temperature rankings in November since 2000. (Right) November 2012 daily temperatures compared to average.

In terms of precipitation, we reported only five days with rain (or frozen precipitation) this past month with the wettest day being November 13 (see below). This was a big change from October’s Sandy burst that brought a sloppy 5.82”. The annual deficit since January is now at 7.27”.

(Left) Driest Novembers on record since 1872. (Right) November 2012 daily precipitation amounts.


The trace of snow (it was actually sleet) on November 8 was the only daily record set at National (tying a trace reported in 1991). Dulles saw a record low maximum of 43F back on November 7 that tied a record from 1967. The only other record was a daily rainfall one of 0.87” back on November 13 as well as a trace of snow (besting 2008’s 0.78”).

2012 year-to-date

2012 continues to be the warmest year on record for Washington, DC. With the November data, we now have Washington, DC running about 1F warmer than the second place year of 2010, which is marginally ahead of 1991 as well.

November pattern

The break in the twelve-month streak of warmer-than-normal temperatures on the East Coast resulted from an average weak cool trough that was kept in place by warm ridging in the West and over the northwest Atlantic. This frequent “blocking” pattern was the same one that drove Sandy into New Jersey in late October. While we certainly saw warmer variability at times, the prevailing pattern frequently looked like what the November 1-29 map looks like below.


A look ahead

The National Weather Service is forecasting December to have equal chances of above, below, or near normal temperatures. December is starting off very warm, but another round of colder weather could return as early as this coming weekend or as late as next week.

Link: Latest NWS forecast map

For further information

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:

Reagan National (DCA)

Dulles Airport (IAD)

Baltimore-Washington (BWI)