National Weather Service United States Department of Commerce

The brunt of our heat wave will be in the Thursday through Saturday time frame, with heat index values frequently of 105-110 degrees, and locally as high as 115. Actual air temperatures will be in the mid to upper 90s. Any outdoor work should be done very early or late in the day, to avoid the worst of the heat.
Dangerously hot and humid conditions are expected today through Sunday...with peak afternoon heat index readings topping out from 100 to 115 degrees. An EXCESSIVE HEAT WARNING remains in effect along and west of a Taylorville line for this afternoon through Saturday afternoon. Further east, an EXCESSIVE HEAT WARNING has been issued to be in effect from Thursday afternoon through Sunday afternoon. If you are planning to be outdoors, limit strenuous activities and spend more time in the shade or air conditioned buildings.
A Severe Thunderstorm Watch has been issued for locations along and southwest of a Macomb to Springfield to Carlinville line through 9pm. This includes the cities of Springfield, Jacksonville, Winchester, Rushville, Beardstown, Havana, and Canton. As severe thunderstorms move through western Illinois, there is potential for wind gusts around 60 mph.