Extreme heat returns to northern Illinois this week

Extreme heat is expected across the Stateline over the course of the next week. Temperatures in the low-to-mid 90s will combine with high dewpoint temperatures to create potentially dangerous conditions. An EXTREME HEAT WARNING is in effect for all of our Wisconsin counties from noon today through 7p Tuesday. We also have the same warning in effect for Jo Daviess, Carroll, Stephenson and Whiteside counties from noon today through 10p Wednesday. Finally, a HEAT ADVISORY is in effect for the rest of the Stateline from noon today through 10p Wednesday. 

These heat headlines are issued when heat index temperatures are expected to be or exceed 105 degrees for a prolonged period of time. Dewpoints in excess of 70 degrees will combine with temperatures in the 90s to create what is expected to be our first dangerous heatwave of the summer 2026 season. As seen in the graphic below, 4 days of heat indices over 100 degrees are expected. This is thanks to a strong area of high pressure camping out to our south.  

Today, expect a high near 92 degrees, with heat indices approaching, if not exceeding 100 degrees. Partly cloudy skies will give way to enough sunshine to make the heat feel extreme at times. Additionally, a gusty southerly wind will allow us to warm quickly into the 90s this afternoon. 

So, let's talk heat safety. NEVER leave pets or children unattended in vehicles! Make sure to look before you lock. Check on neighbors, elderly and those without air conditioning. They are the most susceptible to heat related illnesses. Limit outdoors time during peak heating. Find shade and drink plenty of water.

Finally, know the difference between heat exhaustion and heat stroke. Heat stroke is a medical emergency. If you or someone you know suffers a heat stroke, dial 9-1-1 immediately!