Forecast: Severe Thunderstorm Watch to 8 p.m. Wednesday

The National Weather Service issued a severe thunderstorm watch for most of northeastern Illinois and northwestern Indiana through Wednesday evening.

The watch started at 1 p.m. and lasts until 8 p.m. for virtually the entire Chicago area, including DuPage, Kane, Cook, Lake, Will and McHenry counties in Illinois, as well as Lake and Porter counties in Indiana.

According to the National Weather Service, isolated to scattered thunderstorms are possible across the area with wind gusts greater than 40 miles per hour. But the chance of storms in any particular area is only about 30 percent.

The areas with the best chance of storms developing would be south of a line from Rockford to Joliet to Rensselaer, Ind., on Wednesday afternoon, with a good chance of storms becoming severe, the weather service said.

More widespread thunderstorm activity is possible later, with a 20 percent chance Wednesday night into Thursday morning, and a 40 percent chance on Thursday, though they are not expected to be as severe.

Wednesday's high is expected to be around 90, though cooler into the mid-80s near the lake. Peak afternoon heat indices could reach 101 to 105. Lows will fall into the 70s Wednesday night and top off in the high 80s on Thursday. Friday will again see a high in the upper 80s, cooler near the lake.