Without a doubt, this August was one of our hottest months ever in North Texas. Day after day, from late July through the middle of August, temperatures raced to the century-mark. They had a head-start with overnight lows barely dropping into the 70’s for just a few hours around sunrise.
Our August heat wave was not broken, but ‘bent’ on the 18th when Denton reached 93 and DFW reached 96. By then, we had achieved a top-ten streak of 18 100-degree highs in a row. The longest consecutive 100+ streak was 42 days in the killer heat wave of 1980.
The hottest temperature recorded at Denton as well as DFW was 107 degrees on August 23rd, tying the record set in 1952. It was also the highest temperature reached at DFW since August of 2008, and the 7th highest temperature ever recorded at DFW. The all-time hottest temperature at DFW was 113 degrees, reached two days in a row in late June of 1980.
As we neared the end of the month, a bona fide cold front finally broke the back of our stubborn high-pressure heat dome with strong gusty thunderstorms boiling up along the leading edge of the front on the afternoon of August 24.
The last week of August was a lot more reasonable than the first 3 weeks. But during those first 3 weeks, we were on track to beat at least two, if not all three ‘average’ records: Average High- 102/Rank #3. Average Low- 80/Rank #1. Average Temperature- 91/Rank #1. When all the numbers are in, August of 2010 will probably be ranked in the top 5 hottest Augusts on record.
Why so hot? The global wave pattern in the jet stream has been modified by a drop in ocean temperatures in the East-Central Pacific known as La Nina. This new oscillation has been particularly dramatic with ocean temperatures dropping substantially in a relatively short period of time.
Presuming the trend continues, La Nina is not good news for Texas. It generally means warmer-than normal temperatures and below-normal precipitation through the fall and winter months. Similar patterns have put North Texas into drought conditions during the cooler months of the year, setting the stage crop failures, water shortages and wildfires the following summer. Now is not too soon to start planning for impacts of a prolonged La Nina drought, just in case.