HOUSTON (AP) — Triple-digit temperatures more commonly seen in the throes of summer and not in the spring were making an unwelcome visit to Texas and other parts of the southeastern United States this week, placing millions of Americans under extreme heat warnings.

“Definitely more like August this week than May,” Cameron Self, a meteorologist with the National Weather Service’s office in the Houston and Galveston area, said Tuesday.

A very strong ridge of high pressure over the south-central United States that is centered over the Gulf of Mexico will be responsible for the extreme heat.

For the next six to 10 days, much of south central and the southeastern United States will be warmer than normal, with the highest temperatures occurring over parts of Texas and Florida, Self said.

Some parts of southeast Texas could easily break daily record highs and some could come close to breaking their monthly record highs, Self said.

Areas like Houston that are closer to the Gulf of Mexico could have their temperatures “modified somewhat” because water temperatures are still cool enough, but parts of Texas farther west of the Gulf are going to see temperatures well over 100 degrees, Self said.

It’s not uncommon to get a day or two with temperatures around 94 or 95 degrees in May in Houston.

“But getting long stretches of temperatures well in the 90s that usually holds off till June,” Self said.

“There’s a chance that this could go into next week or longer,” Self said.

Trump signed an executive order renaming the Gulf of Mexico as the Gulf of America. The order only carries authority within the U.S. Other countries and international institutions continue to use the name the Gulf of Mexico.