Gusty winds and lightning strikes caused the power outages about three a.m. About 15,000 customers lost power.
Green Bay was the hardest hit, with more than 12,000 customers without power. Outages were also reported in Kewaunee and Sturgeon Bay.
WPS says it has been able to restore power to all but 500 customers Green Bay.
The company says it isn't sure when it will be able to restore their power.