Enjoy these cooler, drier September days while you can. Climate outlooks from the national Climate Prediction Center are strongly favoring above-normal temperatures for the 6-to-10-day period of September 14th through 18th. Precipitation outlooks are slightly favoring above-normal conditions, but will then shift to drier-than-normal conditions. This should mean fewer muggy days with lower heat index values. The average September temperatures across Indiana – based upon the 1991-2020 period – range in the 60s with daytime highs between 75°F and 80°F. Therefore, even if the climate outlook holds true, above-normal temperatures in September should be more tolerable than in July or August.
Modified growing degree-day (MGDD) accumulations since April 1 currently range from slightly above around 2500 units in northern Indiana to slightly over 3200 units in southern Indiana (Figure 1). This is around 80 to 140 units above normal in the northern part of the state and 50-100 units below normal in the southernmost counties. Figure 2 show comparisons of this year’s MGDD accumulations compared to recent years.
Beth Hall
Indiana State Climate Office
