The National Weather Service says chances for rain and thunderstorms will return to the region beginning tonight and continue through Saturday across the Ohio Valley and Mid-Mississippi River Valley.
The greatest opportunity for widespread rainfall is expected Thursday and Friday. Forecasters say Southern Illinois could receive between 1.5 and 2.5 inches of rain through Saturday night, with lower amounts expected farther south.
Once the rain moves out, a significant heat wave is expected to develop. High temperatures are forecast to climb into the 90s by Sunday and remain there through at least the first part of next week.
Combined with dew points in the 70s, heat index values could reach 100 to 105 degrees on Sunday. Even hotter conditions are expected Monday and Tuesday, when heat index readings may climb to between 105 and 110 degrees.
The National Weather Service says heat advisories may be needed if those forecasts hold and urges residents to stay hydrated, limit outdoor activity during peak afternoon hours, and monitor forecasts for updated heat information.