Excessive Heat — Union, Illinois

2024-07-04 · Union, Illinois

Wider weather episode

Heat indices of 105-114F were observed in much of Southern Illinois on the 3rd and 4th while the I-64 corridor only reached heat advisory criteria on the 4th. Strong moisture advection raised dew points to the mid to upper 70s both days. The highest observed heat index was 114F on the 4th at the Cairo Regional Airport AWOS. Late afternoon thunderstorms in Southern Illinois on the 3rd lowered heat indices for the evening while thunderstorms moved through Southern Illinois mid-morning on the 4th, temporarily delaying daytime heating.

Source: NOAA Storm Events Database, event_id 1201466. Narrative written by the NWS forecast office that issued the report.