An excessive heat warning is in effect from noon Thursday through 8 p.m. Saturday for about the southern third of Lower Michigan. The excessive heat warning includes a line from Grand Rapids to Flint and all points south into Ohio, Indiana and Illinois.

Excessive heat warning in magenta, heat advisory in orange. (National Weather Service)

Today will be just on the verge of excessive heat by 3 p.m. There may be some leftover clouds this afternoon from diminishing thundershowers. The clouds and thundershowers should keep temperatures from getting too hot.

Friday is a different story. The hot air moves in aloft and should kill any leftover Thursday night storms. The sky will then turn sunny and temperatures will swelter. Temperatures will warm into the mid-90s in the excessive heat warning area. With the humidity factored in, the heat index will be 105 degrees to 110 degrees Friday afternoon.

Saturday will be another super hot day, especially for areas from I-94 and southward. Saturday should be an instant replay of Friday for Detroit, Ann Arbor, Jackson, Kalamazoo, Battle Creek, Lansing and possibly Grand Rapids and Flint.

North of the excessive heat warning is a heat advisory for the central third of Lower Michigan. The heat advisory includes the Thumb, Saginaw, Bay City, Midland, Mount Pleasant, Muskegon and Ludington. The heat index will be just five degrees lower than the excessive heat warning area. Expect the air to feel like 95 degrees to 105 degrees Friday afternoon.

The hot and humid air will lead to hazardous weather conditions for the elderly, people with health conditions , children in the sun and outside workers. If possible, reschedule strenuous activities to early in the morning or just before sunset. If you can wait until Monday, much cooler air will be here then.

Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency, and you should call 911.

It’s amazing we still need to remind about this fact: Children and pets should never be left unattended in vehicles under any circumstances. Temperatures can reach deadly levels in a matter of a few minutes.