And of course, the saying goes that, “April showers bring May flowers.” In D.C. (as recorded at National Airport -- DCA), while April is a moderately wet month, at least in number of days with precipitation, it’s not super wet. Just enough to get the growing season going though!
Keep reading for more in this first installment of a year-long series of posts detailing specific statistics on climate norms, extremes, and averages for the each month in Washington, D.C…
The April average* rainfall of 3.06” (previously 2.77” from 1971-2000) is not astounding compared to some of the months that follow during the warm season, when thunderstorms can drop several inches in hours or tropical remnants threaten. But the clash of cool and warm air masses can still create memorable storm events during the month.
The maximum daily rainfall for April is 3.21”, falling on the 26th in 1889. There has been only one other day surpassing 3” in the month -- 3.04” on the 14th in 1970. A recent comparative, the 4.66” that fell on September 30, 2010, was only the third-greatest daily rainfall in that month. And for further comparison, the greatest all-time daily rainfall is 6.39” on August 23, 1933. 13 days in April have had daily totals of 2” or greater.
Snowfall in the month is almost non-existent at the lowest elevations in the area, like DCA. There have been eight days in the entire climate record of D.C. with greater than 1” of snow in April. The last time 1”+ fell was 1924, when the recording station was downtown. Once north and west of the city, odds go up slowly, and generally according to elevation. Why the lack of snow? Warming temperatures, of course…
If not before April even begins, we fully say good-bye to freezing temperatures (none have happened at DCA past April) until the fall. D.C.’s last freeze is roughly April 11 according to the NWS. But, only 11 out of 30 years from 1981-2010 witnessed an April freeze. The latest freeze on record came on the 29th in 1874. The latest freeze at DCA occurred on the 21st in 1956.
Thankfully, particularly for those who love the transitional months between temperature extremes, big heat often does not arrive in force in April. We do taste 80 or higher here and there, but before the vegetation fully kicks in, and with some cooler air masses around, it’s not often oppressive.
30-year (1981-2010) Averages / Overall (All history) Averages...
Highs 70 or above: 11.2 / 10.3
Highs below 60: 7.6 / 9.4
Highs 80 or above: 3.6 / 3.4
Highs 90 or above: 0.4 / 0.4
Lows 32 or below: 0.6 / 1.5
Lows below 40: 4.2 / 7.3
Days with a trace of rain: 15.2 / 15.3
Days with .1” of rain or more: 6.5 / 6.4
Days with .5” of rain or more: 2.2 / 2.2
Days with 1” of rain or more: 0.6 / 0.6
All-Time Records (High / Low)...
Highs 70 or above: 20 (1954) / 1 (1874, 1904)
Highs below 60: 19 (1901) / 1 (1994)
Highs 80 or above: 11 (1976) / 0 (10 years)
Highs 90 or above: 5 (1960, 1976) / 0 (111 years)
Lows 32 or below: 7 (1874, 1896, 1899, 1943) / 0 (61 years)
Lows below 40: 21 (1907) / 0 (7 years)
Days with a trace of rain: 22 (1937) / 6 (1976)
Days with .1” of rain or more: 12 (1874, 1920) / 0 (1985)
Days with .5” of rain or more: 6 (1895, 1937, 1983) / 0 (15 years)
Days with 1” of rain or more: 3 (1899, 1918) / 0 (71 years)
Daily climate records for National Airport (DCA), 1871-present
- See selected and additional statistics compiled for this post (Excel)
*All averages, unless otherwise noted, refer to the 30-year period of 1981-2010.
**All instances of monthly temperature average, daily temperature average or daily precipitation average refer to the 1971-2000 climate normals as presented by the National Weather Service. NWS smooths some averages without daily data in a method described here. Monthly rainfall is a simple average and new 1981-2010 data is used here. NWS data on temperature averages should update shortly and will be reflected in these posts.
While numerous local climatology statistics including daily, monthly, and seasonal normals and records are available from National Weather Service Baltimore/Washington, there are myriad other pieces of information which help frame the story. Rather than attempt to recreate what is already available, this series of posts will act as a companion to most information presented there.
This is the first installment of a series of living documents. Over the next year, each month will be broken down in a similar or evolving way. As input is taken from the community, some items may be added to or changed in older postings. These postings will be updated as necessary to reflect changes when needed. Other articles may also become part of this series.
Feel free to share thoughts or additional data you may be interested in seeing.
Article last updated: April 8, 2011.