October 2012 was the 12th month in a row of warmer-than-normal monthly temperatures at Washington National Reagan Airport (DCA).
The monthly difference from normal this time was only about 1.5 degrees warmer as the month was quite mixed between warm and cool periods.
While it was the 27th warmest October on record, it was the third warmest of the 2000s. Precipitation of 5.82” - thank you, Sandy - also pushes Oct 2012 to the third wettest of the 2000s.
And here are the rankings since 2000:
We hit 80+ for high temperatures five times in October, but most of the month was spent with highs in the 60s and 70s. We dipped into the 40s for lows thirteen times and in the 50s twelve times.
The volatility was high over the month with 39% of the days running colder-than-normal and 61% of the days running warmer-than-normal. All of the area airports reported record daily precipitation totals associated with Sandy, but Baltimore-Washington’s (BWI) 5.51” total was also the wettest of any day in October history there, beating 1922’s 4.38”.
The only other records in the area were a record low maximum at Dulles of 51 on Oct. 8 and a record low temperature at Dulles of 30 on Oct. 13.
We almost experienced a cooler-than-normal October as the prevailing pattern featured lots of high-latitude blocking (high pressure ridging in the far north that displaces cold air southward) up around the North Pacific, North Atlantic, and North Pole. The resulting effect was stronger cool troughing (southward dip in the jet stream) toward the middle of the nation instead of us. Many parts of the Midwest and South are reporting their first cooler-than-normal month in over a year. But D.C. continues its stretch of now twelve months in a row!
2012 continues to be the warmest year on record for Washington, DC. With the October data, we now find DCA running 1.4 degrees warmer than the now second place year of 2010. That is down .2F from its margin through the end of September, but still well ahead.
A Look Ahead
The National Weather Service is forecasting November to have equal chances of above, below, or near normal temperatures. The current round of forecast guidance suggests a cooler-than-normal first 1/3 of November, a mixed middle third, and then maybe a warmer final third of the month as some of those blocking patterns described earlier fade.
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: