Summer’s barely begun, but dangerous heat is taking hold this week.

The National Weather Service is calling for a high of 97 Tuesday in Vicksburg with a heat index of at least 105, meteorologist Greg Garrett said during a statewide weather briefing Monday.

“The heat is going to be a problem,” Garrett said. “We’re looking at heat indices around 105. It’s going to expand and Tuesday is going to be the hottest day.”

The above average temperatures are being caused by a high-pressure system that has also been holding off typical early June late afternoon thunderstorms, Garrett said.

“Lows at night are not going to drop below the mid 70s. We’re going to be for the most part sunny and hot,” Garrett said, adding that rain could return later in the week.

Such a high heat index makes activity outside not only uncomfortable but dangerous, Warren County Emergency Management Agency director John Elfer said.

“Obviously, if you’ve got to work or if you want to exercise outside, you need to do that as early in the morning as you can and then get out of that heat during the middle of the day and the afternoon,” Elfer said.

The high temperatures and humidity mixed with sun exposure can cause heat related illnesses.

Some of the warning signs of heat exhaustion include headache, dizziness, fainting, weakness, irritability, thirst, nausea or vomiting. Heat stroke, which is more severe, can cause confusion and seizures.

People suffering heat stroke also might stop sweating despite not having their body temperature decrease.

“You need to recognize the signs of a heat stroke or heat exhaustion. A heat stroke can be fatal,” Elfer said.

While staying inside in the cool is the better option, Elfer recommended anyone who must spend time outside Tuesday wear light-colored, loose-fitting clothing and drink plenty of nonalcoholic drinks.

“If you’ve got to be outside, you want to have the appropriate work rest cycle. You need something to drink about every 15 minutes,” he said.