From the ABC 7 Weather team

Record low this morning, but was it a chilly July?

July 30, 2014 - 08:22 AM
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July by the numbers.

The debate around town this morning has been about the best way to describe this morning's temperatures. Would you call it cool? Chilly? Crisp? Pleasant? Perfect? Well, if you live around Dulles Airport, you could call it record-breaking cold. The temperature briefly dipped to 48 degrees.

 

(Dulles Temperatures and Dewpoint this Morning)

 

Here's a look at morning low temperatures across the area.

 

(Morning Lows)

 

The old record at Dulles for July 30 was 51 degrees, set in 1981. The unusually chilly temperatures also managed to break the July 29 record, dipping below the previous mark at 11:58 p.m. Tuesday night. National Airport bottomed out above its record low of 56. Martinsburg, W.Va., hit a record low and Baltimore broke its record low with 55 degrees. 

 

(Records at Dulles)

So why has this fall-like weather made a mid-summer appearance? A trough in the upper atmosphere has drawn in cooler air from the north into the Mid-Atlantic. It has made it's way unusually far south for this time of the year. Many records were broken in the East.

 

(Preliminary Record Lows via CoolWx.com)

 

Typically, high temperatures are in the upper 80s in late July in D.C. While we will gradually see temperatures warm up today and tomorrow, the overall pattern keeps us cool to near average through mid-August.

(6 to 10 day Temperature Outlook NOAA)

If you're thinking to yourself that this is a cool July, you're right. As of this morning, Dulles has averaged 74.7 degrees this month, about two degrees cooler than normal. At Reagan National, the average temperature is a bit warmer at 79.8 degrees, right about average. Still, this July is the coolest we've enjoyed since 2009. There were nine days of 90 degree or higher temperatures at National Airport this month, including a high of 99 on July 2nd.  At Dulles, there were just five 90 degree days this month.

If we look ahead to August, climatologically speaking, we will start the month with an average high of 88 degrees and end it with an average high of 84. August is the last meteorological month of summer, with slightly fewer minutes of daylight.

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