Record heat followed by big temperature drop

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We are nearly one-third of the way through Meteorological Fall but typical fall weather has yet to arrive.  In fact, it is going to feel more like July and early August for the end of September and beginning of October.

We can thank the heat due to an upper-level hot dome that will be moving over the Mississippi/Ohio River valleys.  It will send temperatures to the 90°s from central Indiana to northern Louisiana.

Upper-level hot dome develops

During this stretch of heat, it appears Indianapolis could reach 90° for three consecutive days, constituting the third “heat wave” of 2019.

It starts as early as Monday where temperatures are forecast to reach the upper 80°s to lower 90°s around central Indiana.

Forecast high temperature Monday.

It looks like Tuesday will be the warmest of this heat wave.  Temperatures are projected to top out 18° to 20° above normal.  The normal high temperature Tuesday in Indianapolis is 72°.  A little simple math shows the high temperature reaching 92°

One thing that will help, as compared to July and August, is the amount of moisture in the low levels of the atmosphere.  While yes, it will be uncomfortable with dew point temperatures in the middle 60°s, we are not talking dew points in the 70°s which could send the heat index in to the lower 100°s.  Instead, the heat index is only going to be a degree or two above the actual temperature.  So the peak heat index should top out in the lower to middle 90°s.

Forecast peak heat index


If our forecast verifies, record high temperatures are going to fall Monday, Tuesday and Wednesday.  Current high temperature records for Indianapolis:

  • September 30: 89° – 1971
  • October 1: 89° – 1897
  • October 2: 89° – 1953

Forecast high temperature:

  • September 30: 90°
  • October 1: 92°
  • October 2: 90°

If you dig a little deeper in to the numbers, this will smash the record average temperature for the same time period.  The current record average temperature for September 30 through October 2 is 76.5° from 1884.  The forecast average temperature (averaging low and high temperature) for the same dates is 80.3°.  For comparison sake, the normal average temperature is 61.2°.


Long range computer models suggest we get back to normal temperatures by the end of the week and in to the weekend.  It will be a big shock to the system as temperatures will drop 45° from the high temperature Tuesday to the low temperature Saturday morning.  With luck, this will be the last of needing to use the air conditioner for several months.


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