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Posted at 10:30 AM ET, 08/ 6/2009

July Recap: After Cool Start, Summer Gets Real

By Dan Stillman

* Heat on Horizon: Full Forecast | NatCast | Later: Life of a T-Storm *

July's unusually cool and comfortable beginning might have had members of the Real World house in Dupont Circle thinking, "Hey, summer in D.C., not so bad after all." Eventually, though, summer stopped acting polite and started getting real.

Three factoids in particular, as observed at Reagan National Airport (DCA), stand out as ones to remember July 2009 by...

* The temperature didn't reach 90 until July 12.
* It was the first rain-free Fourth of July since 2005.
* It was the fifth driest July on record.

...Though July 14 may take the cake for the most surprising stat of the month.

What happened on the 14th? Keep reading for the rest of the July recap...

The dew point, a measure of how much moisture is in the air, dropped to 39 degrees on the 14th, an incredibly low number for summertime. Only twice before -- on July 1, 2007, and July 1, 1988, had the dew point at DCA dipped into the 30s, according to the National Weather Service's Steve Zubrick. In fact, as was the case through much of June, the dew point spent a good portion of the month's first three weeks near 60 or lower -- far more comfortable than July's more typical mid-to-upper 60s.

Humidity wasn't the only thing missing from the early and middle parts of July. The lack of 90-degree days in June (2) continued right on into July. Not until the 12th did the thermometer touch 90, the latest in the month that's happened since 1998. Prior to the 12th, most days saw highs only in the low-to-mid 80s, even two days in the 70s, with just one day in the upper 80s (88 on the 7th).

And rain?... Almost non-existent. By the end of the day on the 22nd, only 0.26" had fallen for the month, more than 2 inches below the normal amount at that point in July.

It wasn't until the second half of the month that summer finally started to find its groove. The 16th featured the month's highest high temperature at 96 degrees. And by the end of the month 7 days had recorded a maximum temperature of 90 or above, still only about half of the month's normal value. Overall, July finished just over 2 degrees below normal.

Along with the warmer temperatures came increased humidity -- dew points hovered in the mid-60s to near 70 for much of the month's final 10 days -- and some rain. The 0.56" on the 23rd was the month's highest daily total and helped knock the month off what had been a record-dry pace. Still, the month's overall total of 1.07" was good enough to qualify July 2009 as the fifth driest on record, and the first month since March 2009 with below-normal rainfall.

All weather data were those recorded at Reagan National Airport (DCA). For more data, see the National Weather Service's July climate summaries for National, Dulles and BWI.

Related LInks:
A Cool Summer Here, But Not Everywhere
Record Low Dew Point?
D.C. - A Sweet Spot for This Summer's Weather

By Dan Stillman  | August 6, 2009; 10:30 AM ET
Categories:  Local Climate, Recaps  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Wet and Cool Today, Heat on Horizon
Next: The Short Life of a Thunderstorm

Comments

Yes, we were having a GREAT summer until the "much-needed-rain" crew started messing things up with their "precious" humidity after the 15th. Now, looks like we'll have to "wring" our way through August and who-knows-how-much of September.

Judging by the deluges of April--June, they should have held their collective tongues until Labor Day weekend at the earliest.

Posted by: Bombo47jea | August 6, 2009 12:00 PM | Report abuse

The comments to this entry are closed.

 
 
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