October's Temperature Flip Flop

From A/C to cranking up the heat and firing up the wood stove for the first time, all in the same week. Welcome to October folks! In southern Illinois, September may mark the official start to fall on the calendar, but the month often features a lot of summer-like weather. October and November are the two big transition months in the later half of the year, where the battle between summer and winter occurs. So far, October 2018 has featured one of the more epic battles I can remember with record breaking heat and humidity through the first ten days, but then turning to patchy frost just two days later.

Temperature Rankings Through First 11 Days of October
Paducah, Evansville, and Cape Girardeau all with the warmest starts to October on record

The change between summer and fall has been swift here in the middle of October. The 71º for a morning low on October 10th ties an all-time October record for warmest low temperature.
Fast forward to October 12th, the mercury dipped into the 30s for the first time this season. That's a 35º difference in morning lows in just two days.

Now, for the burning question, what's the rest of the month hold? Are we done with the heat and stuck with the cold? Get ready for one BIG flip flop. In weather, there's always a pairing, and we call these "couplets". Where there's a ying, there's a yang. If there's extreme heat, there's extreme cold somewhere.

First 10 days of October vs. Normal

The pattern that has brought the heat to the east, is now shifting out west. Cool weather has arrived for the first time this season east of the Rockies, and it's here to stick around the rest of the month. 

Rest of October: Projected Temperatures vs. Normal