Area Forecast Discussion

KEY MESSAGES

- A dangerous late season heat wave with high temperatures near or at record levels will begin today and continue through most of the week.

- A Heat Advisory will be in effect this afternoon through Wednesday evening for the entire area. The Heat Advisory may need to be extended to Thursday or Friday as well.

- Cooler and less humid conditions will arrive Sunday and Monday, along with a 20 to 40% chance of showers and thunderstorms on both days.

DISCUSSION

Issued at 1052 PM CDT Mon Sep 14 2026

The much-advertised late season heat wave begins today, as very strong H5 ridging becomes centered over the area. The latest ensemble guidance continues to show H5 heights around 600 dm and 850mb temperatures peaking around 20-22C each afternoon through at least Thursday. Both values are at the climatological maximum for the time of year. This will yield maximum temperatures in the middle to upper 90s (possibly isolated low 100s) and minimum temperatures in the lower to middle 70s during this time. Both the forecast high and low temperatures will approach or break record hot/warm values this week. See the Climate section below for more details. Humidity values will be greatest today and Wednesday, with dew point temperatures reaching the lower 70s. This will yield widespread heat index values around 105 degrees today and Wednesday. The current Heat Advisory runs through 7 PM CDT Wednesday.

On Thursday and Friday, dew point temperatures will begin to draw downward into the middle to upper 60s due to moisture being extracted from the soil. Air temperatures will still be in the upper 90s for most locations, but there is more uncertainty regarding if the heat index values will breach the triple digits. However, given the late season nature of the heat and impacts to outdoor activities, an extension of the Heat Advisory through the end of the work week is possible.

The H5 ridge will begin to break down this weekend, but high temperatures will still reach the lower to middle 90s on Saturday. However, there is better model agreement that some noticeable relief from the heat will arrive beginning Sunday into early next week as frontal boundary attempts to move south through the area. This will yield high temperatures in the upper 80s to lower 90s on Sunday and lower to middle 80s on Monday. Additionally, there may be enough moisture and forcing from the cold front to kick off isolated to widely scattered showers and thunderstorms on both days.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 1110 PM CDT Mon Sep 14 2026

Little change from previous forecast. The winds have become calm at KPAH and they are already near saturation. Used a TEMPO to mention MVFR fog 09Z-13Z just to be safe. Elsewhere, winds are persistent and fog is still not expected. South southwest winds will increase to 8-10kts in the morning and will occasionally gust 14-17kts through the afternoon at all sites.

CLIMATE

Issued at 1052 PM CDT Mon Sep 14 2026

Record high temperatures for Tuesday, Sep 15: CGI: 96 (2025) MDH: 106 (1939) EVV: 99 (1939) PAH: 102 (1939) POF: 101 (1939)

Record high temperatures for Wednesday, Sep 16: CGI: 99 (2019) MDH: 101 (1927) EVV: 99 (1898) PAH: 97 (2019) POF: 101 (1927)

PAH WATCHES / WARNINGS / ADVISORIES

IL...Heat Advisory from 11 AM Tuesday to 7 PM CDT Wednesday for ILZ075>078-080>094. MO...Heat Advisory from 11 AM Tuesday to 7 PM CDT Wednesday for MOZ076-086-087-100. Heat Advisory until 7 PM CDT Wednesday for MOZ107>112-114. IN...Heat Advisory from 11 AM CDT /noon EDT/ Tuesday to 7 PM CDT /8 PM EDT/ Wednesday for INZ081-082-085>088. KY...Heat Advisory from 11 AM Tuesday to 7 PM CDT Wednesday for KYZ004-005-007>022. Heat Advisory until 7 PM CDT Wednesday for KYZ001>003-006.