Winter Storm Warning vs. Watch vs. Advisory

A watch means it might happen. A warning means it will, and it's serious. An advisory means it will, and it's a nuisance. Here is every NWS winter alert in plain words.

By Petar M., editor · Updated October 18, 2026 · How we research

In this guide (4)

Watch, warning, advisory: the short version
Every winter alert the NWS issues today
Is there still a "Heavy Snow Warning"?
What each alert usually means for school

Watch, warning, advisory: the short version

Watch: conditions are favorable for a hazardous storm, but it isn't certain. The NWS issues a watch when it is at least about 50% confident, often a day or more ahead. Time to plan.
Warning: a hazardous storm is expected and dangerous. Issued at about 80% confidence or more. Time to act.
Advisory: winter weather is expected and will cause problems, but less severe than a warning. Also issued at about 80% confidence. Time to be careful.

The amounts that trigger each one are set by your local NWS office. A Winter Storm Warning takes much more snow in the Northern Plains than in the Southeast, for the same reason schools there need more snow to close.

Every winter alert the NWS issues today

Alert	What it means	Effect on the calculator
Blizzard Warning	Strong wind (35 mph or more) and falling or blowing snow keep visibility under a quarter mile for three hours or more.	Raises it the most
Ice Storm Warning	Damaging ice from freezing rain, usually around a quarter inch or more.	Raises it the most
Winter Storm Warning	Heavy snow, sleet or ice, or a mix, meeting the local office's warning criteria. Also used for lighter amounts that will have a big impact.	Raises it a lot
Lake Effect Snow Warning	Heavy lake-effect snow in narrow bands downwind of the Great Lakes (used by some regions).	Raises it a lot
Extreme Cold Warning	Dangerously cold air or wind chills.	Raises it a lot
Winter Weather Advisory	Snow, sleet, freezing rain or blowing snow that will cause problems, but below warning level.	Raises it some
Cold Weather Advisory	Cold or wind chills that are hazardous, but below warning level.	Raises it some
Winter Storm Watch	A significant winter storm is possible in the next few days; details are still uncertain.	Raises it a little
Extreme Cold Watch	Dangerous cold is possible in the next few days.	Raises it a little
Snow Squall Warning	A short, intense burst of snow and wind with sudden whiteouts, for a small area and about an hour.	Raises it a little

Alert names from the NWS alert list (api.weather.gov). Definitions summarized from NWS Instruction 10-513. The last column describes how our model weights each alert; see how it works.

Is there still a "Heavy Snow Warning"?

No. The NWS stopped issuing Heavy Snow Warnings in 2008; heavy snow is now covered by theWinter Storm Warning. Several other names you may still see on older pages are also gone:

Snow Advisory, Freezing Rain Advisory, Lake Effect Snow Advisory: now part of the Winter Weather Advisory (2008 and 2017).
Blizzard Watch and Lake Effect Snow Watch: now part of the Winter Storm Watch (2017).
Wind Chill Warning, Watch and Advisory: renamed Extreme Cold Warning, Extreme Cold Watch and Cold Weather Advisory in October 2024. Wind chill and school closings.

The Lake Effect Snow Warning was folded into the Winter Storm Warning in 2018, then brought back in October 2019, and each region decides whether to use it.

What each alert usually means for school

Winter Storm Watch the evening before: the storm may not arrive in time, or may shift. Districts rarely close on a watch alone; check again in the morning.
Winter Storm, Ice Storm or Blizzard Warning overnight: the strongest signal there is. These nights produce most snow days, and districts sometimes decide the evening before.
Winter Weather Advisory: often means a delay rather than a closure, especially in snowy places. In places where snow is rare, an advisory with ice can close schools.
Extreme Cold Warning: can close or delay school with no snow at all, depending on how cold it gets at bus time.

The calculator checks the active alerts for your county every hour and combines them with the forecast amounts. An alert alone doesn't make a snow day: a Winter Storm Warning for snow that ends at 9 PM matters less than an advisory for ice at 6 AM.

Check your district

See tomorrow's chance of a closure or delay for your ZIP code. Open the calculator, or find your state or city.