Heat advisory: Temperatures are near a danger zone. What should you know?

Forecasters say Rock Hill area residents and others in the Carolinas should heed safety precautions, with high heat and humidity expected for the first half of this week.

National Weather Service meteorologists say heat indices of up to 105 degrees are forecast Tuesday, with 100-degree heat indices possible Monday and Wednesday.

The heat index is the actual feel of the combined impact of temperature and humidity.

Heat advisories are issued when the heat index reaches 105 degrees, but National Weather Service meteorologist Trisha Palmer said Monday that caution is needed even when the index doesn’t quite reach that level.

“Research from surrounding areas has shown that heat-related illnesses seem to peak just below advisory thresholds,” Palmer said. “That is, people tend to take advisories seriously and follow heat safety precautions, but if there’s no advisory, people aren’t as cautious.”

Forecast high temperatures are 92 degrees Monday, 96 on Tuesday, and 94 on Wednesday. But humidity levels will be higher earlier this week than they were over the weekend, Palmer said.

A few late-afternoon and evening thunderstorms are forecast Tuesday, with a higher chance of storms Wednesday. That is when a cold front is expected to push into the Rock Hill area from the northwest.

The front is predicted to break the heat wave, with high temperatures cut back to the mid and upper 80s for the rest of the week.

Showers and thunderstorms will remain in the forecast Thursday, and after a break Friday, precipitation could return again for the weekend.

Steve Lyttle on Twitter: @slyttle