The relief was palpable.
Richmond, a city known for its swampy wetness, had its least wet June in a decade, according to Sean Sublette, chief meteorologist for the Richmond-Times Dispatch. Because dry air removes heat faster than moist air at night, the city also recorded its lowest temperatures in June since 2012.
Washington also missed his usual share of scorching hot days and sauna nights. On Independence Day, the dew point – a measure of humidity – fell 49 degrees, a surprisingly low value. Average dew points in July are in the upper 60s.
Any dew point below 60 is refreshing in the mid-Atlantic at this time of year. End of June, they even dived in the 30s in Washington, which is virtually unheard of.
The nation’s capital has yet to experience a heat wave this summer, defined as three days in a row with 90-degree weather. It has only logged 12 days at 90 degrees so far, six less than normal. The last summer with these few so far was 2009, and there have only been two heat waves, with the first not occurring until August.
Capital Weather Gang readers noticed the subdued heat and are don’t complain:
“It was the sweetest summer I can remember in a long time,” tweeted @NattyBDC.
“I loved this weather! Last summer seemed relentlessly hot and very little rain in July,” tweeted @uwchelsita.
The number of 90-degree days is also down in New York and Boston.
New York had seven — an almost normal number, but Boston only saw two, three less than average.
“[S]Since mid-May, it’s been nothing but great almost every day,” tweeted Eric Fisherchief meteorologist for Boston television station WBZ.
The respite from the heat can be attributed to the shape of the jet stream, which is the high-altitude wind current that divides warm and cold air and is the highway of storms.
As the jet stream bulged north over the western and central United States, it plunged into the eastern United States, frequently crossing the mid-Atlantic. This allowed a fairly steady stream of dry, cool Canadian air to seep into the northeast.
The jet stream swirled around the Pacific Northwest, which also experienced a relatively mild summer – a welcome break from last year’s historic heat wave.
But for areas south of the jet stream – in the central and southern United States – the heat has been painful and persistent. Texas was particularly hard hit.
The good weather in the northeast comes at a cost, however. Because it stayed north of the storm’s track, very little precipitation fell. A moderate to severe drought developed from eastern Connecticut to southern Maine.
The mid-Atlantic, meanwhile, has been in a prime position for heavy rain – located just along the path of the jet stream. Washington and Richmond have been hit by intense storms in recent weeks. The Washington area also experienced several instances of flooding, as did many places in the southwest.
While much of the mid-Atlantic and northeast avoided long periods of excessive heat and temperatures hovered around the 30-year average, temperatures have still been high relative to averages. historical.
Average summer temperatures so far this year in Richmond, Washington, New York and Boston rank among the 45 highest in the past 125 to 150 years. In other words, the weather this summer would have been abnormally hot a century ago, even though it’s considered normal now – a testament to the influence of human-caused climate change.
Computer models signal a warming trend in the coming week.
Richmond and Washington are expected to see highs in the 90s, while New York and Boston are expected to be near the 90s.
Rather than dipping over to the northeast, the jet stream is expected to flatten out and move slightly northward – moving enough to allow some heat to billow into the region.
As we head into August, it’s unclear if the jet stream will move further north, causing the northeast to bake, or if it will start to dip again.
The National Weather Service leans slightly toward a warmer than normal first half of August for much of the eastern United States.
Although it is warming up a bit, average temperatures begin to drop very slowly in late July across much of the northeast. Average temperatures begin to drop on July 21 in Washington and July 26 in Boston.
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