Heavy storms this morning left about 55,000 customers without power in the eastern part of the Twin Cities, and another 15,000 without power in the west metro.
Xcel Energy spokeswoman Mary Sandok says crews are out assessing the damage.
"We are getting reports of poles and wires down that would be a result of high winds bringing branches and trees down on lines," she said. "There was also lots of lightning with this storm so there could have been some lightning strikes that caused some of the damage to our system as well."
Sandok says it could take into tomorrow or the next day to restore power, depending on how severe the damage is to power lines.
A power outage in downtown Stillwater led to long delays for commuters this morning.
Many traffic lights in the downtown area are not working because of power outages caused by last night's thunderstorm, according to the city's public works department. The Stillwater Lift Bridge was down at the time of the power outage, so it remains open to motorists, said Minnesota Department of Transportation spokesperson Kevin Gutknecht.
Transportation officials said they do not know when the power will be restored.
The National Weather Service issued a Flash Flood Watch for much of central and eastern Minnesota beginning at 4 a.m.
Storms will increase Tuesday, especially as the afternoon heats up. Highs on Tuesday will warm into the low to mid 90s in southern Minnesota. Cooler weather is on tap for Wednesday, although more rain is likely.
(MPR reporter Madeleine Baran and meteorologist Bill Endersen contributed to this report.)