Sizzling start to September: Heat Advisory issued for northern Illinois

Heat Advisory:

The heat and humidity are making a big comeback across the Stateline today, prompting a Heat Advisory from 12PM until 9PM for Winnebago, Boone, Ogle, Lee, DeKalb, McHenry, Carroll, and Whiteside Counties. As of this moment, the heat alerts do not extend into southern Wisconsin. 

  

Temperatures this afternoon will climb to around 90 degrees, but the bigger story will be the humidity. With dew points in the low to mid 70s, it feel considerably hotter, with heat index to 100 degrees or higher for several hours this afternoon. If you are spending time outdoors, be sure to take frequent breaks, stay hydrated, and limit strenuous activity during the hottest part of the day. Don't expect much of a cooldown tonight. Temperatures will be slow to drop, only settling into the low 70s. 

Hot Start to September:

The heat won't completely let up after today. A strong late-summer ridge will drift east but at the same time, leaving low-level flow out of the southwest. This will keep temperatures running well-above average through the second half of the week. 

Highs will end up in the low 90s Wednesday before easing slightly into the upper 80s Thursday and Friday. While air temperatures may come down a bit later in the week, the humidity isn't going anywhere. Heat index values are expected to climb into the 100 to 105 degree range on Wednesday, then remain above 90 degrees Thursday and Friday, making it feel several degrees hotter than the thermometer suggests. Again, be sure to practice heat safety during the prolonged hot stretch.