Heat Wave Peaks Today, Excessive Heat Warning in Effect

After such an unseasonably warm start to our Friday, highs are forecast to climb into the mid and even upper 90’s. And once you add the humidity into the equation, heat index values will make it very dangerous to be outside for prolonged periods of time. This will most likely end up being the warmest day of the year so far. In fact, today's high will be just a few degrees shy of the daily record high of 100° set back in not too long ago in 2011.
As of this morning, the National Weather Service added the rest of our viewing area, which includes Winnebago, Boone, McHenry, Green, Rock, and Walworth counties, to the Excessive Heat Warning. This warning is set to remain in effect until tomorrow evening around 7 PM CDT.

Excessive heat warnings are issued when maximum daytime heat index values are forecast to reach 110° or greater with overnight minimum heat index values of 75° or greater for at least 48 hours. Heat index values are suppose to eclipse the 100° mark by noontime and stay above 100° through the rest of the afternoon and into this evening. So if you have any outdoor activities or have to be outside for a prolonged period of time, please find ways to stay cool and hydrated.

For Rockford, the heat index could be as high as 112°. Overnight lows are once again expected to only fall into the upper 70’s to low 80’s throughout the area, meaning little relief from the oppressive heat will be felt. Similar to this morning, we will once again have an unseasonably warm start to the morning for our Saturday. Heat index values overnight are forecast to stay between 85° and 90° for a majority of the night. Saturday afternoon will feature more of the same in terms of hot and humid weather. This time, starting off the day with plenty of sunshine before we see increasing clouds during the afternoon as a cold front approaches the area.

Daytime highs will likely be a few degrees cooler, with most of the region topping out in the mid to upper 90’s. Heat index values will once again climb to between 105° and 110° by tomorrow afternoon. Once this potent cold front passes through Saturday night into Sunday, it will not only bring a good chance for thunderstorms, but also a cooler and much more comfortable air mass for the end of the weekend!