1st heat wave of the season possible from Chicago to New York

PHOTO: A traveller is silhouetted by the setting sun while running past a wind partition in the bus lanes at Denver International Airport late Wednesday, June 26, 2019, in Denver.PlayDavid Zalubowski/AP
WATCH What is the Heat Index?

It's officially been summer for less than a week, but the temperatures from Chicago to New York are making it feel like the height of the season.

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Chicago’s Midway International Airport hit 90 degrees Wednesday for the first time since last September.

Denver hit 90 degrees for the first time since last September, as well. And New York's LaGuardia Airport hit 90 degrees for the first time this year.

PHOTO: A heat wave is possible from Denver to New York over the next few days. ABC News
A heat wave is possible from Denver to New York over the next few days.

For it to be considered a heat wave, it needs to hit 90 three days in a row in Chicago, NYC and Philadelphia. More 90s are in the forecast over the next few days.

The heat will even reach parts of the Upper Midwest, where the Twin Cities could be in the mid 90s by this weekend.

Severe weather outlook

More than 4 inches of rain fell just south of Chicago since Wednesday night, producing flash flooding, stranding vehicles and prompting water rescues.

Up to 8 inches of rain fell in southwest Missouri, producing flash flooding there as well.

There were 116 damaging storm reports Thursday around the country, including Oregon, where trees feel on homes in Salem, and hail covered ground in Portland.

PHOTO: Severe weather is possible across the northern U.S., especially in Montana and northwest of Chicago. ABC News
Severe weather is possible across the northern U.S., especially in Montana and northwest of Chicago.

Severe storms are expected Thursday from the Great Lakes all the way to the northern Rockies. There are more storms expected near Chicago, all the way to the Twin Cities and west to most of Montana.

The biggest threat is damaging winds, hail and a few tornadoes.