A series of powerful thunderstorms over the weekend across the upper Midwest may have given a reprieve from the heat wave gripping the eastern half the country, where hundreds of thousands across Michigan and Wisconsin are without power while residents clean up the damage.

The thunderstorms brought hurricane-force wind gusts in two rounds on Friday night and Saturday from South Dakota into southern Minnesota, with a separate cluster of storms stretching across Wisconsin and into Michigan.

"I was so scared, I really thought I was going to die," Lisa Gast told FOX11.

Gast, who was driving from work to her home in Mountain when the first round of storms moved through, said in her 20 years living in the community about 65 miles northwest of Green Bay she's never experienced a storm like the one Friday night.

"I wanted to get home to my family," she said.

HEAT WAVE ACROSS US COULD SEE FEELS-LIKE TEMPS REACH TRIPLE DIGITS THIS WEEKEND, NWS WARNS

As of Sunday morning, more than 564,000 power outages were reported in Wisconsin and Michigan as a result of the severe weather, according to poweroutage.us.

The vast majority of outages were reported in Michigan, where DTE Energy said 375,000 customers were without power as of 6 a.m. on Sunday due to the two waves of severe weather that moved through southeast Michigan Friday and Saturday.

"I know it is very hard and inconvenient to live without power any time, but especially in today's record heat levels," spokesperson Heather Rivard told FOX2.

Rivard said that crews working 16-hour shifts around the clock were calling for back up, with several crews arriving Saturday afternoon from northern Indiana. Officials have answered calls for more than 1,500 downed power lines due to the storms.

"There may still be additional wires down out there. We encourage you, if you see a downed line, do not go near it and call DTE right away," Rivard told FOX2.

Electric service is expected to be restored to all affected customers by the end of the day Tuesday, according to DTE.

The extreme heat helped trigger severe weather throughout Metro Detroit and southeastern Michigan, with areas hit by flooding, 60 mph winds and egg-sized hail.

Temperatures have since dropped and are expected to be in the low-80s to start the week.

ILLINOIS, MASSACHUSETTS POLICE DEPARTMENTS TELL CRIMINALS TO STAY INSIDE DURING HEAT WAVE

In Wisconsin, utility companies warned that power could be out for days, especially in the Fox Valley area as some electrical infrastructure needs to be rebuilt.

Matt Cullen, a spokesman for both WPS and We Energies, told FOX11 the priority is addressing downed power lines that are still electrified.

We Energies said on Twitter that they have restored power to more than 33,000 customers as of Saturday afternoon after "extensive damage."

CLICK HERE FOR THE FOX NEWS APP

The line of severe thunderstorms that impacted South Dakota into Minnesota were known as a derecho, which is a widespread, long-lived, straight-line windstorm that is associated with a fast-moving group of severe thunderstorms, according to AccuWeather.

"The derecho and other severe thunderstorms erupting over the Midwest on Saturday were fueled by the sweltering heat and humidity surging over a large part of the nation," said stated AccuWeather Senior Meteorologist Kristina Pydynowski.