COLUMBIA, S.C. — A scorching heat wave weeks before the start of summer is gripping the Deep South with several cities reporting the hottest temperatures ever recorded in May.

High temperatures were at least 100 degrees Fahrenheit Monday in Florence and Columbia, S.C.; Augusta, Ga.; and Jacksonville and Gainesville, Fla. It was the fourth day of temperatures in that range in a week. Savannah’s high of 102 degrees was a record for all of May and hotter than any day so far this year in Phoenix, as the same weather pattern bringing the unprecedented heat to the Southeast also has the desert southwest unusually cool.

While unusual for late May, this kind of heat isn’t unheard of for the Deep South in the middle of summer. Officials did not report a large number of people sickened by the hot weather, even over the long Memorial Day weekend.

The above normal temperatures will continue through the middle of the week, said National Weather Service meteorologist Michael Emlaw in Charleston. But May doesn’t mean the whole summer will simmer in the Southeast.

A big factor will be whether the area can shake loose from the unusually dry weather pattern.

“The lack of rain is making it hotter. With the ground dry, all of the sun’s energy is put into heating the atmosphere instead of some of it being used to evaporate moisture in the ground,” Emlaw said.