CLARKSVILLE, TN (CLARKSVILLE NOW) – With a heat index up to 113 degrees today, Montgomery, Stewart, Houston, Dickson counties are among those under an Excessive Heat Warning.

The warning from the National Weather Service is in effect from 11 a.m. to 7 p.m.

NEWS ALERTS: To get free breaking news alerts on your phone, text the word NEWS to 77000.

“Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities,” the warning said.

The high will be around 100 today. That will dip slightly on Thursday, but bounce back to about 100 Friday, Saturday and Sunday.

Clarksville forecast

Here’s the day-by-day forecast:

Today: Sunny and hot, with a high near 99. Heat index values as high as 109. West southwest wind around 15 mph, with gusts as high as 25 mph.

Tonight: A 30 percent chance of showers and thunderstorms, mainly before 2am. Partly cloudy, with a low around 73. West southwest wind 5 to 10 mph.

Thursday: Patchy fog before 7am. Otherwise, sunny, with a high near 96. Heat index values as high as 99. Light west northwest wind becoming north northwest 5 to 10 mph in the morning.

Thursday night: Mostly clear, with a low around 69. North wind around 5 mph becoming calm in the evening.

Friday: Sunny and hot, with a high near 99. Calm wind becoming south southwest around 5 mph in the morning.

Friday night: Mostly clear, with a low around 72. South wind around 5 mph.

Saturday: Sunny and hot, with a high near 99. South southwest wind 5 to 10 mph.

Saturday night: Mostly clear, with a low around 75. South wind 5 to 10 mph.

Sunday: Sunny and hot, with a high near 98. West southwest wind 5 to 10 mph.

Sunday night: Mostly clear, with a low around 75.

Monday: A 30 percent chance of showers and thunderstorms. Mostly sunny and hot, with a high near 97.

Monday night: A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 73.

Tuesday: A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 96.