Watch vs. Warning
A watch means the risk of hazardous weather has risen but its timing, location, or occurrence is still uncertain: be prepared. A warning means hazardous weather is occurring, imminent, or likely and threatens life or property: take action now. An advisory covers events that are occurring or likely but less serious than a warning.
Why It Matters
The three words tell you what to do. A watch is the time to make or review a plan. A warning is the time to carry it out.
National Weather Service Alert Levels
| Alert | What it means | What to do |
|---|---|---|
| Watch | The risk of a hazard has increased significantly, but its occurrence, location, or timing is still uncertain. Hazardous weather is possible. | Have a plan ready and listen for later information and possible warnings. |
| Advisory | A hazard is occurring, imminent, or likely, but conditions are less serious than a warning. It can cause significant inconvenience and could threaten life or property if caution is not exercised. | Use caution. |
| Warning | A hazard is occurring, imminent, or likely and poses a threat to life or property. | Take protective action immediately. |
Source: NWS San Angelo: Watch, Warning, and Advisory Explained
Frequently Asked Questions
Which is worse, a watch or a warning?
A warning. A watch means hazardous weather is possible. A warning means it is occurring, imminent, or likely, and you should take protective action immediately.
What is the difference between a tornado watch and a tornado warning?
A tornado watch covers a group of counties where tornadoes are possible over the next several hours: stay alert and be ready to shelter. A tornado warning means a tornado has been spotted or radar shows a storm circulation that can produce one: take shelter immediately.
What is a weather advisory?
An advisory is for a hazard that is occurring, imminent, or likely but less serious than a warning. The conditions can cause significant inconvenience and could threaten life or property if you are not careful.
Related Terms
SPC Outlook
Severe weather forecasts issued by the Storm Prediction Center categorizing risk levels from Marginal (1) to High (5). Outlooks cover tornadoes, damaging winds, and large hail for 1-3 days ahead and highlight where organized severe weather is most likely.
Tornado
A tornado is a violently rotating column of air in contact with the ground, extending from a thunderstorm. Tornadoes are rated from EF0 to EF5 on the Enhanced Fujita scale by the damage they cause. Most last less than 10 minutes, but the strongest can stay on the ground for more than an hour.
Flash Flood
A flash flood is a rapid and extreme flow of high water into a normally dry area, or a rapid rise in a stream or creek above flood level, that begins within about six hours of its cause. The usual cause is intense rainfall, but a dam failure or an ice jam can also trigger one.
Blizzard
A blizzard is a storm with sustained winds or frequent gusts of 35 mph or more and falling or blowing snow that frequently reduces visibility to below a quarter mile, lasting 3 hours or longer. The National Weather Service definition has no snowfall or temperature requirement: wind and visibility make a blizzard.
Red Flag Warning
A Red Flag Warning is a National Weather Service alert that weather conditions could cause extreme fire behavior. It is issued when those conditions are occurring or expected within 24 hours. Typical criteria combine dry fuels with sustained winds of 15 mph or more and relative humidity of 25% or less, and exact thresholds vary by state and local office.
Small Craft Advisory
A Small Craft Advisory is a National Weather Service alert for winds or seas that are hazardous to small boats in coastal and Great Lakes waters. The wind and sea thresholds are set separately for each geographic area. There is no precise definition of a small craft: any vessel that the conditions could affect counts.
Tsunami Warning
The highest alert level issued by a tsunami warning center, meaning a dangerous tsunami is expected or already underway and people in the threatened zone should move inland or to high ground immediately. The lower levels are an advisory (dangerous currents near the water), a watch (a distant event may pose a threat, stay alert), and an information statement (no threat expected).
Watch vs. Warning: Guides and Explainers
These explainers connect this definition to real-world forecasting and decision-making.
In-depth guide
Watch vs Warning vs Advisory vs Outlook: NWS Weather Alerts Explained
Learn the difference between a weather watch, warning, advisory, and outlook, what a Special Weather Statement means, and when to prepare versus take immediate action.
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Helpful Tools and Hubs
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Sources
Explore Other Terms
IFR
Instrument Flight Rules govern flights conducted under instrument procedures and can be used in clear weather too. Separately, the IFR weather category means a ceiling from 500 to less than 1,000 feet and/or visibility from 1 to less than 3 statute miles, with lower values classified as LIFR. Legal operating requirements depend on airspace, regulations, equipment, and pilot qualifications.
Typhoon
A tropical cyclone with sustained winds of 74 mph or greater in the Western Pacific. Typhoons are meteorologically identical to hurricanes; the different name reflects only their geographic location.
Lake Effect Snow
Intense, localized snowfall produced when cold air moves across relatively warm lake water, picking up moisture and heat. Lake effect snow can produce snowfall rates of 2-4 inches per hour and create dramatic differences in accumulation over short distances.
King Tide
King tide is a popular, non-scientific name for an exceptionally high tide. King tides happen when the higher tides around a new or full moon coincide with the Moon's closest approach to Earth, called perigee. They can flood low-lying coastal areas on a clear day, and they raise the water level any storm surge is added to.
AQI
The Air Quality Index (AQI) is the U.S. Environmental Protection Agency's color-coded scale for reporting air pollution. It has six categories, from Good (0 to 50) to Hazardous (301 and higher). Values of 101 and above are unhealthy, first for sensitive groups and then, as the number rises, for everyone.
El Niño and La Niña
El Niño and La Niña are the warm and cool phases of a recurring climate pattern in the tropical Pacific called the El Niño-Southern Oscillation (ENSO). During El Niño, the trade winds weaken and the central and eastern tropical Pacific runs warmer than average. During La Niña, the trade winds strengthen and the same waters run cooler. Both shift weather patterns worldwide.
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