UPDATE: The weather bureau said a prolonged period or consecutive days of heat can cause a cumulative effect of heat stress. Those prone to heat stress will need to take frequent breaks, especially when shade or air conditioning is not available. Strenuous outdoor activity may lead to heat injuries such as heat stroke, heat exhaustion and heat cramps.
Heat stroke is an emergency and those suffering from it should call 911, according to the weather bureau.
The hottest stretch of this week's heat wave is expected to impact southwest Lower Michigan today and Thursday. Highs are expected to climb into the 92-97 degree range both days, except it will be cooler along the Lakeshore. The Grand Haven-area forecast calls for highs in the mid 80s each day through Sunday, with highs dropping to around 78 on Monday.
Temperatures are only expected to drop into the mid 70s overnight.
The combination of heat and tropical humidity levels will cause heat index values to climb to around 105 both days.
Local governments remind residents that there are options available for people to keep cool during the heat. This includes Grand Haven, where officials said their public buildings are open during business hours; and the Village of Spring Lake, which is offering Barber School from 8 a.m. to 5 p.m.