After the warmest and top ten driest March on record , April brought back a sense of weather normalcy. While relatively warm (1.5F warmer than normal) and dry (1.1” drier than normal), the month didn’t produce many extremes. But compared to March, April offered more weather variety: with more cooler-than-normal days and at least a few rainy/cloudy days.

For precipitation, April 2012 was drier than normal, but the estimated 1.92” was still much more than the driest 0.03” from 1985. The wettest April on record continues to be 1889 with 9.1”.

Washington Reagan National (DCA) did not report any temperature or precipitation records this month. But Baltimore tied the 2002 record of 90F on April 16. Washington Dulles had a record high low temperature of 61F on April 16 and then a record low high temperature of just 47F just a week later on April 23.

Distribution of high and low April temperatures at Reagan National Airport

Comparison with March

Comparison of number of 70+ and 80+ days in April and March at Reagan National Airport

Prevailing jet stream during April (NOAA)

And May?

Despite the very warm first handful of days in May, the pattern trends are suggesting a cooler situation by next week and maybe even deep into the month. Developing blocking patterns in high latitudes of North America means we would see more chances for cooler Canadian air transport in the weeks ahead. I’m not ready to suggest that May could be our first cooler-than-normal month since October, but this is probably the best chance since that time.

The National Weather Service offers a very large shoulder shrug with EC for both temperature and precipitation throughout our area. EC means Equal Chances of below, normal, or above normal temperatures (33.3 chance each).

Additional reading

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)

Historical Washington, DC data provided by Speedwell Weather and NOAA. See also: Ian’s excellent rundown on April climatology