Heat Advisory vs Extreme Heat Warning: In Plain Words

The name changed in 2025

The NWS says it is renaming its Heat Watch and Heat Warning products to improve messaging, as part of the Hazard Simplification Project.

On March 4, 2025, the NWS implemented these changes:

• Excessive Heat Watches were renamed to Extreme Heat Watches.
• Excessive Heat Warnings were renamed to Extreme Heat Warnings.

The NWS says this effort integrates years of public and partner engagements and social science research to improve and evolve its alerting system, and that renaming these Watch and Warning products also enables clear and timely decision support.

The rename list covers the Watch and the Warning. The current NWS “Understanding Heat Alerts” page still lists the third product under its familiar name: Heat Advisory.

So if an older page, a saved alert, or a search result says “Excessive Heat Warning,” read it as the product now called an Extreme Heat Warning.

The three heat alerts, as the NWS words them today

The NWS lists these heat-related products on its “Understanding Heat Alerts” page:

• Extreme Heat Warning — Take Action!
• Extreme Heat Watch — Be Prepared!
• Heat Advisory — Take Action!

Heat Advisory — Take Action!

A Heat Advisory is issued for dangerous heat conditions that are not expected to reach warning criteria.

The NWS wording for a Heat Advisory is:

• Consider postponing or rescheduling outdoor activities, especially during the heat of the day.
• If you must be outside, be sure to drink plenty of water and take frequent breaks in the shade.
• Stay in a cool place, especially during the heat of the day and evening.

Extreme Heat Watch — Be Prepared!

An Extreme Heat Watch is issued when conditions are favorable for an extreme heat event but its occurrence and timing is still uncertain.

The NWS wording for an Extreme Heat Watch is:

• Plan to suspend all major outdoor activities if a warning is issued.
• If you do not have air conditioning, locate the nearest cooling shelter or discuss staying with nearby family or friends who have air conditioning.

Extreme Heat Warning — Take Action!

An Extreme Heat Warning is issued when extremely dangerous heat conditions are expected or occurring.

The NWS wording for an Extreme Heat Warning is:

• Avoid outdoor activities, especially during the heat of the day.
• If you must be outside, be sure to drink plenty of water and take frequent breaks in the shade.
• Stay indoors in an air-conditioned space as much as possible, including overnight.
• Check on family and neighbors.

The difference, in one look

• Heat Advisory: dangerous heat conditions that are not expected to reach warning criteria.
• Extreme Heat Watch: conditions are favorable for an extreme heat event, but its occurrence and timing is still uncertain.
• Extreme Heat Warning: extremely dangerous heat conditions are expected or occurring.

A Watch is about being prepared, because the event is still uncertain. An Advisory and a Warning are both headed “Take Action!” by the NWS — the Warning is the one for extremely dangerous heat.

Why the trigger numbers are local

Each National Weather Service Forecast Office issues some or all of the heat-related products as conditions warrant.

NWS local offices often collaborate with local partners to determine when an alert should be issued for a local area.

The NWS gives this example: residents of Florida are much more prepared for 90°F+ weather than residents in Alaska.

That is why this page does not print one nationwide temperature or heat index number for these alerts. Use the alert and the criteria from your own local Forecast Office.