A heat advisory is in effect for most of Southeast Michigan until 8 p.m. Tuesday as temperatures continue to climb, according to the National Weather Service. 

An extreme heat warning for Macomb, Oakland and Wayne counties will be in effect from 8 a.m. Sunday to 8 p.m. Tuesday. 

Heat index values of 100 to 105 are possible in the advisory area, and near or over 105 for areas under the warning.

The NWS says people should avoid outdoor activities when an extreme heat warning is in effect. 

An extreme heat watch issued Friday for Southeast Michigan has since been canceled and replaced by the heat advisory.

Near-record, or record-breaking, temperatures on Sunday and Monday will reach into the mid to upper 90s with little chance of cloud cover to provide relief.  

Officials in several Metro Detroit communities have opened cooling centers for the next few days to help residents take shelter from the dangerous heat. Learn more about where these centers are and when they'll be open here.

Across the U.S., over 140 million Americans will be under the highest-level extreme heat alerts by Sunday, officials said. 

A heat wave is a period of unusually hot weather that lasts more than two days, according to the NWS.