Weather 101: Know the difference – heat advisory vs. excessive heat watch vs. excessive heat warning

Weather 101

3 kinds of heat alerts can be issued for NW Arkansas and the River Valley. Here's a look at the criteria necessary for each of them!

Throughout the summer, various heat alerts may be issued by the National Weather Service (NWS) when abnormally hot temperatures move into the area.

There are three kinds of heat alerts that may be issued for our area: heat advisory, excessive heat watch, and excessive heat warning. Each one has its own criteria for being issued in NW Arkansas and the River Valley and it can change based on your location within the United States.

Heat advisory

In NW Arkansas and the River Valley, heat advisories are issued when air temperatures reach 103°F or the heat index (the feels-like temperature) hits 105°F for at least 3 hours. Heat advisories mean there is some risk for heat exhaustion and heat stroke.

Excessive heat watch

If the forecast calls for even more extreme heat, an excessive heat watch may be issued. In our region, an excessive heat watch will be issued when the maximum heat index may reach at least 110°F or the air temperature is expected to be 105°F or more for a minimum of 3 hours. An excessive heat watch can be issued up to 72 hours ahead of the criteria being met.

Current heat alerts as of 6:45 PM, July 26 2021.

Excessive heat warning

When the air temperature is expected to reach 105°F or the heat index is forecasted to be 110°F for at least 3 hours and will occur within the next 12 hours, an excessive heat warning will be issued for our area.

Excessive heat warnings mean there is a high risk of heat stroke or heat exhaustion if you are working outside and not being careful.

If you suspect yourself or someone else is suffering from heat exhaustion or heat stroke, here is what you should do.

Depends on your location!

The air temperature and heat index thresholds can change based on your location. This is because certain areas of the country are warmer than others on average. Here is a look at the heat index criteria across the country necessary for heat advisories to be issued.

Heat index criteria for a heat advisory as of July 26, 2021.

Send us your questions!

If there is something about the weather you would like to know, send us an email – weather@knwa.com and we’ll answer in a future episode of weather 101!

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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