Watch vs warning: what the US National Weather Service means
Follow your local authorities. In an emergency call 999/911.
The US National Weather Service (NWS) uses a few short words with very different meanings. Using flooding as the example:
Watch: be prepared
A Flood Watch is issued when conditions are favourable for flooding. The NWS says it does not mean flooding will occur, but it is possible. Use a watch to get ready: check your kit, know your route out, and keep your phone charged.
Advisory: be aware
A Flood Advisory is issued when flooding is not expected to be bad enough for a warning, but may still cause significant inconvenience. If caution is not exercised it could lead to situations that threaten life or property.
Warning: take action
A Flood Warning is issued when flooding is imminent or already happening. A Flash Flood Warning is issued when a flash flood is imminent or occurring. The NWS says that if you are in a flood-prone area you should move immediately to high ground. A flash flood is a sudden violent flood that can take from minutes to hours to develop, and it can happen even where it is not raining.
The short version
- Watch: it could happen. Prepare now.
- Advisory: it is a nuisance. Take care.
- Warning: it is happening or about to. Act now.
Check each alert's own text for the hazard it names.
What to do next
Ready.gov advises listening to emergency alerts, NOAA Weather Radio or local alerting systems for current instructions during flooding, and not walking, swimming or driving through flood water.
Sources
- NWS, Flood Warning vs. Watch, accessed 2026-10-23.
- Ready.gov, Floods, accessed 2026-10-23.
Last checked: 2026-10-23