What's the difference between a heat advisory and a heat warning? NBC6 meteorologist explains what it means for South Florida

This summer, South Florida has seen some of the highest temperatures on record.

But what is the difference between a heat advisory and a heat warning and how does it differ from county to county?

Here's everything you need to know:

What's the difference between a heat advisory and a warning?

Miami-Dade County has different criteria for heat index values than Broward County.

In Miami-Dade, if the heat index is 105° for two hours or more, a heat advisory will be issued. But if it is 110° for two hours or more, a heat warning will be issued.

On Sunday, for example, the heat index in Miami-Dade was set to reach between 108 and 112 degrees.

In Broward, however, the threshold is a little higher.

If the heat index is at least 108° for two hours or more, a heat advisory will be issued, but if it is 113° for two or more hours then a warning is issued.

What happens to the body under extreme heat?

Amidst record-breaking temperatures across South Florida, the Chief Medical Officer of Broward Health Medical Center weighed in on what happens internally when your body experiences extreme heat.

Dr. Joshua Lenchus explains that when temperatures become extreme, sweat can no longer evaporate, which makes it harder for you to cool down.

The evaporation of sweat off of skin is a cooling mechanism that people naturally undergo when they become hot, he said.

Heat cramps, which are caused by a loss of water and electrolytes, can be an early sign that you should hydrate and cool down.

When your internal body temperature has risen and the symptoms are not addressed quickly enough, it can progress to heat exhaustion, Lenchus said.

What are some ways to help combat the heat?

It's important to keep cool in order to avoid heat-related illnesses.

Here's some tips that Lenchus advised for staying safe:

• Avoid outdoor activities between 10 a.m. and 2 p.m.
• Take frequent breaks from the heat
• Hydrate before, during, and after outdoor activities
• Wear bright, loose clothing

You can even check out some of Miami-Dade's many cooling sites that will help you stay safe this summer.

Even the water at the beach is hot. Is it safe to swim?

A weather phenomenon called El Nino, combined with climate change, has led to record-breaking temperatures across South Florida. A marine heat wave means that beaches aren't providing relief.

Waters off the southern coast of the Florida reached never-before-seen temperatures in 2023, the National Oceanic and Atmospheric Administration reported.

The ocean water temperatures are expected to rise throughout the summer, and 50% of the water is expected to be undergoing a heat wave by September. Usually, only 10% of the world's oceans are warm enough to meet the criteria for a marine heat wave.

Most years, cooling off by the beach is the natural solution to excessive heat on land. But with waters this hot, is it still safe to swim?

The answer is yes - but with caveats.

Who's most vulnerable during this heat wave in South Florida?

According to the CDC, people with diabetes, sickle cell anemia, heart disease, mental illness, poor blood circulation and obesity are all at elevated risks for heat-related illness.

Those who are most vulnerable should take the following protective measures during extreme heat:

• Stay in air-conditioned buildings as much as you can. Don't rely on a fan as your main source of cooling during extremely hot days.
• Drink more water than usual, even when you're not thirsty.
• Check up on a friend or neighbor and have someone do the same for you.
• Limit the use of a stove or oven.