Take good care of your air conditioner, everyone. In a summer of record temperatures, Florida is in for more brutal heat this week with highs in the 90s and dangerously hot conditions with "feels like" heat indices well into triple digits across the state, according to the National Weather Service (NWS).
An excessive heat warning with heat index values up to 115 degrees is in effect across north and South Florida and Southeast Georgia from 10 a.m. EDT Tuesday until 8 p.m.
An excessive heat watch advisory has been issued for Wednesday across North Florida, with heat index values up to 113 possible.
Central Florida is under a heat advisory from 11 a.m. to 7 p.m., with heat index values up to 112 expected.
Be sure to take precautions. The danger from rising temperatures is getting worse. An average of 700 people died every year in the U.S. between 2004 and 2018 of heat-related causes, according to the CDC, and 3,066 heat-related deaths occurred during 2018-2020. According to data from the National Conference of Citizenship, heat-related deaths in Florida have increased 88% in the last three years.
Stay in air-conditioned spaces as much as possible, the NWS advises. Stay hydrated, and wear sunscreen and protective clothing.
What is an excessive heat warning?
Nationwide, the NWS issues an Excessive Heat Warning when heat index values, the "feels like" temperatures, are expected to be 105-110 degrees or higher for at least two consecutive days and nighttime air temperatures will not drop below 75 degrees, depending on the local climate.
Different areas of Florida have different criteria for issuing excessive heat warnings, such as a heat index forecast of 113 degrees or higher for at least two hours.
A heat index of 103 to 124 degrees can cause heat cramps and heat exhaustion, the NWS said, and possible heat stroke with prolonged exposure and/or physical activity. Heat stroke is extremely likely with heat indices over 125 degrees. If you don't take precautions immediately when conditions are extreme, you may become seriously ill or even die.
On June 1, the Miami-Dade NWS began using new heat advisory criteria for that area that lowered the range of heat indices required to more closely reflect the "significant health impacts from heat" that occur at lower heat index values. In that county only, excessive heat warnings are issued when the heat index reaches 110 degrees or higher for at least two hours. If this is evaluated to be more accurate, the new criteria will be rolled out to the rest of South Florida in 2024.
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What is an excessive heat watch?
The NWS issues an Excessive Heat Watch when an excessive heat event is likely in the next 24 to 72 hours. Excessive heat watches are used when the timing of the heat event isn't nailed down yet.
What is a heat advisory?
The NWS issues a Heat Advisory within 12 hours of the onset of dangerous heat conditions when the heat index is expected to reach 100 degrees or higher for at least two consecutive days and nighttime air temperatures will not drop below 75 degrees, depending on local climate.
What watches and warnings have been issued in Florida?
What is the heat index?
"It's not the heat, it's the humidity," as people in Florida are a little too fond of saying. For the heat index, it's both.
While the temperature tells you how hot it is, the heat index combines the temperature and humidity levels to tell you what the temperature actually feels like outside. Weather apps and forecasters call it the "real feel" or "feels like" temperature, and it's important to know.
When your body gets too hot, it cools itself off by sweating and your body's temperature reduces as the perspiration evaporates. When the relative humidity is high (that's the moisture in the atmosphere), your sweat doesn't evaporate as quickly (or at all) and you feel warmer. When humidity levels are low, your perspiration evaporates more quickly and the "feels like" temperature might feel even cooler than the Fahrenheit number.
"For example, if the air temperature is 100 degrees and the relative humidity is 15%," the National Weather Service explains on their website, "the heat index is 96 degrees."
Keep in mind, the heat index value is for shady locations. "If you are exposed to direct sunlight, the heat index value can be increased by up to 15 degrees," the NWS said.
What is the difference between the heat index and the Wet Bulb Globe Temperature?
The Wet Bulb Globe Temperature (WBGT) is similar to the heat index in that it measures more than just the temperature to give you a sense of what the weather really feels like. But the WBGT measures temps in the sun, not the shade, and includes wind, cloud cover and the angle of the sun to help indicate heat stress for active populations such as outdoor workers and athletes.
You can see WBGT forecasts at weather.gov/rah/WBGT .
