Cool, Miami Is Under Another Heat Advisory

The National Weather Service (NWS) issued a heat advisory this morning for Miami and nearly all of South Florida, cautioning residents that the heat index today could reach or exceed 110 degrees Fahrenheit.

The advisory, in effect from 10 a.m. to 6 p.m. today, covers Miami Dade County, Broward, and Palm Beach counties, warning that the heat index in these areas may top 110 degrees (whew!). While heat advisories were previously issued when the heat index reached 108 degrees, the NWS now issues a heat advisory if the index reaches 105 degrees for a few hours.

The heat index, also known as the apparent temperature, combines two measurements — relative humidity and air temperature — into one number.

As the NWS explains on its website, "When the body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature. Evaporation is a cooling process. When perspiration is evaporated off the body, it effectively reduces the body's temperature. When the atmospheric moisture content (i.e. relative humidity) is high, the rate of evaporation from the body decreases. In other words, the human body feels warmer in humid conditions."

Totday's advisory warns that hot temperatures and high humidity can cause heat illness, advising residents to drink plenty of fluids and take extra precautions when outside, such as wearing lightweight clothing and limiting strenuous activities to early morning or evening.

"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors," the advisory reads.

Last summer marked the warmest on record globally, with extreme temperatures fueling climate-driven disasters across the planet, from wildfires in Canada to mass coral deaths around the Florida Keys. It was so damn hot that Miami received its first ever "excessive heat" advisory and obliterated records for the highest recorded temperatures for seven dates in July.

With the official start of summer still weeks away, temperatures across Miami and in the surrounding ocean waters have already hit record highs.

This is a breaking story and may be updated as events warrant.