There are really only two ways to describe the month we just had in Washington, D.C. — hot and stormy. Meteorological summer got off to a very warm start with numerous storms that dumped an excessive amount of rain across the entire region, and in the immediate metro, especially.
June 2015 will go down in the weather annals as the second wettest and the sixth warmest June on record for Washington, D.C. On top of that, Baltimore-Washington International topped the record books with its wettest June on record by over three inches of rain. An astonishing 13.09 inches fell during the month, and the previous wettest June on record was in 1972, when 9.95 inches of rain fell. Like, 2015, 1972 was also an El Niño year.
Here is the preliminary look at June 2015 differences from average at our local airports. Reagan National Airport ended the month with eight inches more rainfall than we see in a typical June, and BWI ended with nearly 10 inches more than average. That’s a lot of rain!
In terms of temperature, the 78.1 degree average temperature at National was 2.9 degrees hotter than normal — warm enough to earn the place of sixth hottest June on record. Four out of 10 of the hottest June records have occurred since the year 2000. We still have three years hanging onto the list from before 1950, including the 77.5-degree average June from 1874!
June 2015 spent about 40 percent of its days with highs in the 90s and also 40 percent in the 80s, leaving only 20 percent for the cooler 60s and 70s, which were mostly at the very beginning of the month (remember when we thought summer deserted us?). Humidity was frequently higher than normal, so many of those 80s often felt like the 90s in the form of heat index.
After a drier-than-normal May, we caught up big-time in June with rain on 18 out of the 30 days. Three particularly wet days in the month saw over 2 inches of rain. We fell short of the big June record in 2006, but last month is a solid second place. Here are the top ten wettest June periods of all-time at National:
Temperature and precipitation records
Just like we saw in May, there were more record warm minimum temperatures at National than there were at BWI and Dulles. All three climate stations achieved daily rainfall records though. Here is the breakdown:
June 12: Record high minimum of 77F, besting 1947’s 76F
June 13: Record high minimum of 75F, tying 1981, 1984, 2005
June 14: Record high minimum of 78F, beating 76F from 1984 and 1981
June 20: Record rainfall of 2.37″, breaking the 1.35″ set in 1983
June 27: Record rainfall of 2.75″, breaking the 2.59″ set in 1881
June 23: Record rainfall of 0.55″ beating 1974’s 0.48″
June 27: Record rainfall of 1.47″ ties 2006
June 1: Record rainfall of 2.5″ beats 1979’s 2.14″
June 27: Record rainfall of 3.11″ beats 1883’s 2.04″
The weather pattern
The June weather pattern varied at times with more heat in the Eastern U.S., especially for the second and third weeks, but then by the final part of June, ridge pattern shifted back to the Western states. The net result for the overall month included a jet stream pattern that was more north than normal over North America. Cool upper level troughing locked up over the Arctic Ocean and down into the Hudson Bay area (which still has ice on it!).
Below is the estimated national temperature departure from normal map. You can see how most of the country leaned warmer than normal, but that the bigger anomalies were definitely in the West, zeroing in on the Pacific Northwest.
2015 so far
The warm June outcome has moved 2015 above the 30-year average temperature to-date, and into ninth place for warmest years of the 2000s. I’m not sure how we’d ever catch up with the insane 2012 year thanks to its super-warm March period, but never say never in weather — we’ve got six more months to go for 2015.
For precipitation, our super-wet June has pushed 2015 to the third wettest spot behind 2008 and 2003. While we could make a run at second place, which is currently held by 2008, the 2003 high water mark of 31.07 inches for the year will be more difficult to rival since that was the year of Hurricane Isabel. We have over twice as much precipitation as the driest period up to this point since the year 2000 — 2012’s measly 13.12 inches is sitting in last place for the century so far.
For further information
The National Weather Service publishes nice monthly assessments about five days into the start of the next month. You can click on your closest airport location here: