Weather alert: Heat advisory issued for the Miami area. How steamy will it get?

A heat advisory has been issued for South Florida.

The advisory from the National Weather Service will be in effect from 10 a.m. to 8 p.m. Friday. While temperatures are expected to rise to the mid-90s, it could feel as high as 105 when you mix in humidity, according to the weather service.

“It’s going to be another scorcher,” said Lissette Gonzalez, a meteorologist with Miami Herald news partner CBS News Miami. “Super steamy.”

So steamy that the thermometer reached more than 80 degrees in Miami at 5 a.m., and Key West was already in the mid-80s and feeling like the mid-90s.

MORE: It’s feeling like 100 degrees outside. So how cold should you set your A/C thermostat?

What is the heat index?

The heat index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature, according to the weather service.

Last year, Miami-Dade County weather service officials announced plans for raising awareness of environmental extreme heat hazards. Among the initiatives: the declaration of a Miami heat season that runs from May 1 to Oct. 31.

Previously, the weather service issued a heat advisory when the heat index hit 108 degrees. Now, the local weather service in Miami issues a heat advisory if the index is 105 degrees for at least a couple of hours.

Rain chance

The one good part of the forecast: Not much rain is expected Friday. Rain chance is about 10 percent, with anything falling coming after 4 p.m., according to the weather service. That will change on Sunday, when rain chance rise to 50%.

Looking ahead

The heat isn’t ending after Friday. Temperatures in the 90s are also forecast through the weekend and into Monday in South Florida.