‘Oppressive heat’ in store for northern Illinois following tornado watch: National Weather Service

Large portions of northern Illinois were facing a potentially dangerous heat have that could see heat indices up to 110 degrees this week, the National Weather Service said Monday night.

The weather service issued a hazardous weather outlook on Monday night for Winnebago, Boone, McHenry, Lake, Ogle, Lee, DeKalb, Kane, DuPage, La Salle, Kendall, Grundy, Kankakee, Livingston, Iroquois, Ford and parts of Cook and Will counties.

“Oppressive heat and humidity will result in very muggy conditions across the area tonight,” the weather service said.

The dangerous temperatures are expected to extend through Wednesday, with a chance of thunderstorms late Wednesday through Thursday morning, the weather service said.

Earlier Monday, the National Weather Service issued a tornado warning for parts of Kane, DuPage and Cook counties. The warning for Elgin, Streamwood and Hanover Park was in effect until 6:45 p.m. Monday, the weather service said.

Another warning for northeastern DuPage and northern Cook was in effect until 7:15 p.m., the weather service said.

Meanwhile, the National Weather Service had issued a tornado watch for 10 northern Illinois counties through 11 p.m. The counties affected by the watch included Boone, Cook, DeKalb, DuPage, Kane, Kankakee, Kendall, Lake, McHenry and Will.

As northern Illinois braces for intense heat and humidity moving in this week, the National Weather Service earlier in the day warned of possible high damaging winds up to 75 mph and a chance for tornadoes and hail.

Forecasters issued a hazardous weather outlook earlier Monday that said thunderstorms were expected to move into northern Illinois and northwest Indiana Monday afternoon.

“The storms will be capable of producing damaging winds and very large hail. A tornado or two cannot be ruled out,” according to the hazardous weather outlook. “Oppressive heat and humidity will build across areas south of (Interstate 80) this afternoon, when heat index values around 105 or higher are expected.”

The outlook applied to Winnebago, Boone, McHenry, Lake, Ogle, Lee, DeKalb, Kane, DuPage, La Salle, Kendall, Grundy, Kankakee, Livingston, Iroquois, Ford counties as well as portions of Cook and Will counties and northwest Indiana.

Dangerously high heat is expected Tuesday through Wednesday, along with a possible thunderstorm on Wednesday into Thursday morning, forecasters said.

A heat advisory also is in effect Tuesday afternoon through Wednesday evening.