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Posted at 10:47 AM ET, 07/31/2012

Which July in Washington, D.C. felt hotter: 2011 or 2012?


Comparison of 90-degree and higher days at Reagan National Airport during the past two Julys.
As we enter the final day of another record-warm July in Washington, we can at least take solace in knowing that our climatologically hottest month of the year is behind us. Barring an apocalyptic freeze tonight, July 2012 should end up D.C.’s all-time second hottest month on record.

Through July 30, the temperature at Reagan National Airport has averaged 84.1 degrees F. The current gold medalist in our heat competition is July 2011, which averaged a slightly warmer 84.5ºF. With July 2012 set to become our second-hottest July, it will bump July 2010 into third place.

But while this July takes the silver medal for average monthly temperature, which July actually felt hotter to you: July 2011 or July 2012?

Read below for more commentary and statistics on these two most recent Julys...

In 2011, we had 25 days of 90+ temperatures and just three 100-degree days. This month, we’ve had 21 90-degree days but 7 of those climbed to 100ºF or higher (beating out the old monthly record of six 100-degree days in 1930).

And let’s not forget our record 11-day stretch of temperatures 95 degrees or higher that began in late June and peaked on July 7 at 105ºF. That day’s average temperature of 94ºF was D.C.’s all-time hottest on record.

So, which of the last two brutally hot Julys was worse by a subjective measure? If upper 90s and 100-degree days is your metric, then 2012 wins easily. Plus, anyone who spent days without power after the derecho would probably argue that July 2012 felt hotter.

Yet overall – by account of persistent heat and humidity – I still consider July 2011 the worse of the two evil infernos.


July 2012 daily high temperatures in D.C. compared with 2011.
While this July featured historic heat, we were lucky to get intermittent relief from all those 100-degree days. The month started off scorching hot, but two weeks after soaring to a record 105ºF, the thermometer maxed out at a record-cool high of 71 degrees on the 21st. Of course, the temperature rebounded to 100ºF just five days later, but still: that one refreshing day of light rain atoned (somewhat) for the punishing heat that preceded it.


July 2012 daily low temperatures in D.C. compared with 2011.
What really sticks out in my mind about July 2011 was the oppressive humidity that accompanied our hottest days. This year we also had plenty of humidity, but it never felt quite as stifling as during our Sweat Ceiling episode last year. Before July 2011, I don’t recall ever experiencing an oppressive dew point of 81 degrees or a heat index of 121ºF.

It was last year’s high humidity that helped D.C. achieve a record 7 days on which overnight low temperatures failed to drop below 80 degrees – including two 84-degree lows that tied D.C.’s all-time record high minimum temperature. By contrast, July 2012 had four overnight lows of 80ºF or higher – still too many, but perhaps slightly more tolerable.

In conclusion: whether you thought this July felt hotter or cooler than last year is purely subjective. Both months set a number of new heat records, so maybe I’m splitting hairs. But when we consider the overall discomfort level of the month, July 2011 has a slight edge in my book.

How do you think our two hottest Julys stack up? Feel free to comment below.

By  |  10:47 AM ET, 07/31/2012

Categories:  Latest, Extreme Heat, Local Climate

 
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