September 2010 is following in the tradition of this year's June and August: it’s coming in much hotter than normal. Thankfully, the much shorter day length and lower sun angle means 90s instead of 105.
The average temperatures for mid to late September should be a low of about 64 and a high of about 85. We’re going to be running between 5 and 10 degrees above on both at least til Thursday the 23rd.
The map above reveals the usual suspect for this type of stubborn heat: a well entrenched subtropical high aloft that moves little day to day. This one is very large, and will continue to influence weather from the east coast to the Rockies with above average temperatures.
We’ll also have very low rain chances during this period. I cannot rule out an isolated heat-driven storm sometime between now and Wednesday, but the odds on a given day will be below 10%.
By the way, the Autumnal Equinox, the astronomical start of fall, is coming quickly: It will take place 10:09p.m. CDT (Texoma time) on Wednesday 22 September.
I can only hope our weather pattern might “get a clue” sometime soon!