In recent years, excessive heat has caused more deaths than all other weather events, including floods. A heat wave is a prolonged period of excessive heat, generally 10 degrees or more above average, often combined with excessive humidity.
You will likely hear weather forecasters use these terms when a heat wave is predicted in your community:
Excessive Heat Watch – Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.
Heat Advisory – Heat Index values are forecasting to meet locally defined advisory criteria for 1 to 2 days (daytime highs= 100-105° Fahrenheit).
Excessive Heat Warning – Heat Index values are forecasting to meet or exceed locally defined warning criteria for at least 2 days (daytime highs= 105-110° Fahrenheit).