July 2011 Was Hottest Month Ever

July 2011 was the hottest month in recorded history in Washington D.C. July 2010 had set a new record also, but this year the temperatures soared just over another degree on average to achieve an incredibly toasty 84.5F at Washington Reagan National Airport. That is 4.7 degrees hotter than the new 1981-2010 normal or 5.3 degrees hotter than the old 1971-2000 climatological baseline. Also, it is slightly hotter than a normal July for Houston, TX and slightly cooler than a normal July for Dallas, TX. It’s like we were living in a whole different part of the country. As you might expect for a month like this, precipitation ran below normal, but only .7" below the 1981-2010 normal of 3.70" at National Airport. This puts our running deficit over 4" since January 1st. While Washington actually saw the same number of 100-degree days this July compared to last, and both were extraordinarily hot, this one took the cake on pretty much every high-temperature metric. Of those three 100-degree days, one was a record for the date 104F on the 29th. That was the hottest we’ve seen in D.C. since August 17, 1997 when it was 105, and it tied for the 5th hottest all-time. Previously, the second of back-to-back 102s on July 23 also set a new record for the date. Other notable D.C. area 100-degree plus stats for the month include the all-time record high of 105F at Dulles Airport on July 22. Although the records there only go back to 1963, no other day had topped 104 with the last occurrence in 1988. On the same day, BWI hit 106F. That was the highest on record at the current location, and one shy of the all-time Baltimore record of 107. A fourteen day streak of 90-degrees or higher, which now carries on into August.