CHICAGO — Lollapalooza will see a weekend of mild temperatures, with showers and possible thunderstorms rolling in by Friday, forecasters said.

Jake Petr, a meteorologist with the National Weather Service in Chicago, said Thursday will bring sunny conditions with highs in the mid-70s and light winds.

On Friday, temperatures could be slightly warmer, hitting the upper 70s. Some lighter showers are expected to move in during the afternoon, with heavy rain and potential thunderstorms arriving by evening, Petr said.

“When there is rain late Friday, it could be fairly heavy and there could be some ponding on the roadways if that were to happen,” Petr said.

Saturday morning may see lingering showers and thunderstorms, with temperatures in the 70s. Sunday, Petr said, will be mostly dry, but he said he couldn’t “rule out” a light shower in the morning.

In a statement Monday, the city Office of Emergency Management and Communications advised festivalgoers to monitor conditions before heading out and to be aware of extreme weather evacuation sites located in the Grant Park North, Grant Park South and Millennium Lakeside garages.

“With the latter days of the weekend still a few days away, I’d still recommend keeping up with the forecast,” Petr said.

This week began with severe storms across the region. Storms grounded flights, suspended public transportation and left nearly 320,000 ComEd customers without power Monday evening.

The National Weather Service confirmed four tornadoes in Illinois during Monday’s storm.

The four-day music festival kicks off at noon Thursday.

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