Severe thunderstorm watch for Kane, McHenry counties

The National Weather Service has issued a severe thunderstorm watch for a large part of northern Illinois that includes Kane and McHenry counties.

The watch lasts until 2 a.m. The watch area is east of a severe thunderstorm warning area in northern Illinois around Rockford and in southern Wisconsin.

The storms come after two hot and humid days that also brought an air quality alert for the Chicago area until midnight Thursday.

The weather service's forecast for Friday includes an overall 30 percent chance of rain with a high of 83. Then a nice weekend is in the forecast.