The hottest day of the month—and potentially the hottest day of the summer so far—lies ahead of us on Tuesday. High temperatures will rise into the upper 80s and flirt with 90 degrees by the afternoon. It’s going to be hazy, hot and humid. Dew point values will rise into the 70s giving the air a tropical-feel.
Combining our air temperature and relative humidity gives us the heat index. The heat index is more or less a “real-feel” index when outside in a hot and humid airmass. The index Tuesday afternoon will reach the middle and upper 90s across northern Illinois and southern Wisconsin. If you’re going to be outside during the heat of the day, make sure to drink plenty of water and dress appropriately.
By Tuesday evening and night, a cold front will slide through the area. This will bring some scattered showers and thunderstorms.
There is a chance for an isolated stronger thunderstorm or two. Heavy rain and gusty wind are the main concerns. There is a small window for thunderstorm development before the front passes through and our airmass changes again. Cooler, less humid air is on tap for Wednesday through Friday with highs in the upper 70s.
This post was written by Joe Astolfi on July 21, 2014