Ask Storm Team 11: What is the difference between a Heat Advisory and an Excessive Heat Watch or Warning?


Well it is summer-time in the Tri-Cities. While our highest average high temperature over the summer is 86 degrees, we all know it can get much hotter than that.

In today’s Ask Storm Team 11 we break down the difference between a Heat Advisory, Watch, and Warning. 

It is important to know the difference between these different types of heat alerts so you know what to expect to keep yourself and others safe.

First let’s define heat index, as this is a big factor in The National Weather Service issuing these alerts.

The Heat Index is a measure of how hot it actually feels when you factor in the humidity with the temperature. 

Heat Advisory is issued within 12 hours of dangerous heat conditions. An advisory will be issued when the heat index temperature is expected to be 100 degrees or higher for at least two days. Or, when night time temperatures do not give relief and do not drop below 75 degrees.

An Excessive Heat Watch is issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours.

An Excessive Heat Warning in placed within 12 hours on the onset of extremely dangerous heat conditions. Here a heat index of at least 105 degrees is expected for at least two days, or when overnight temperatures do not cool below 75 degrees. 

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