Hurricane Watch vs. Warning: What Each Alert Means and What to Do

When a tropical storm or hurricane heads toward the U.S. coast, two words start showing up on phones, TV crawls and forecast maps: watch and warning. They sound alike, but they ask you to do different things. The short answer: a hurricane watch means hurricane conditions are possible in your area, and a hurricane warning means they are expected. A watch is your signal to get ready. A warning means your preparations should already be finished.

Here is what each alert means according to the National Hurricane Center (NHC) and the National Weather Service (NWS), how the timing works, and what emergency officials advise you to do under each one.

What is the difference between a hurricane watch and a hurricane warning?

Both alerts use the same wind threshold: hurricane conditions, defined as sustained winds of 74 mph or higher. The difference is certainty and time.

• Hurricane watch: hurricane conditions are possible somewhere within the watch area. NHC issues it 48 hours before it expects tropical-storm-force winds to begin.
• Hurricane warning: hurricane conditions are expected somewhere within the warning area. NHC issues it 36 hours before it expects tropical-storm-force winds to begin.

Notice what the clock is tied to. Both lead times count down to the arrival of tropical-storm-force winds of 39 mph, not to landfall or to the strongest winds. NHC’s glossary explains why: preparedness activities become difficult once winds reach tropical storm force, so the alerts are timed to leave you a window while it is still safe to work outside.

A hurricane warning can also stay in effect after the winds drop below hurricane force if dangerously high water, or high water combined with waves, continues.

Watch and warning types at a glance

Source: National Weather Service and National Hurricane Center definitions.

What are tropical storm watches and warnings?

They follow the same logic one step lower on the wind ladder. A tropical storm watch means sustained winds of 39 to 73 mph are possible within 48 hours, and a tropical storm warning means those winds are expected within 36 hours.

Do not treat a tropical storm alert as minor. NWS notes that tropical storms and depressions can also be devastating, and they bring many of the same hazards as hurricanes, including storm surge, flooding rain and tornadoes.

What do storm surge watches and warnings mean?

Storm surge is the abnormal rise of seawater pushed ashore by a storm’s winds. NWS says it is historically the leading cause of hurricane-related deaths in the United States, and surge can travel several miles inland, especially along bays, rivers and estuaries.

Because water, not wind, is the threat, surge has its own alerts:

• Storm surge watch: life-threatening inundation from rising water moving inland from the shoreline is possible in the area, generally within 48 hours.
• Storm surge warning: there is a danger of life-threatening inundation, generally within 36 hours. NWS advises anyone under a storm surge warning to check for evacuation orders from local officials.

NHC may issue surge alerts earlier when strong winds are expected to cut short the time available for evacuations. A surge warning can also cover places that may not flood themselves but could be cut off by flooding nearby. For a broader look at the pressures facing low-lying shorelines, see our explainer on how rising seas are affecting America’s coasts.

What is an Extreme Wind Warning?

This is the most urgent wind alert in the hurricane system. NWS issues an Extreme Wind Warning when extreme sustained winds of a major hurricane, 115 mph or greater and usually associated with the eyewall, are expected to begin within an hour. The instruction is simple: take immediate shelter in the interior portion of a well-built structure.

Can alerts be issued before a storm even forms?

Yes. NWS can issue hurricane, tropical storm and storm surge watches and warnings for a disturbance that has not yet become a tropical cyclone but is forecast to bring tropical storm or hurricane conditions to land. Advisories call these systems “potential tropical cyclones,” a label NHC uses when land could be affected within 72 hours.

Alerts can also continue for “post-tropical cyclones,” storms that have lost some or all of their tropical characteristics but are still producing dangerous conditions. The name on the storm can change; the danger may not.

What should you do during a hurricane watch?

A watch is the time to finish getting ready while conditions are still calm. Drawing on guidance from NWS and the federal Ready.gov program, that means:

• Find out whether you live in an evacuation zone, learn your routes, and decide where you would stay.
• Review your household emergency plan, including anyone who may need extra help.
• Check your supplies, including medication and pet supplies, since you may not have access to them for days or even weeks after a hurricane.
• Bring in outdoor furniture, clear drains and gutters, and put up storm shutters if you have them.
• Charge your phone and backup batteries, and make sure insurance papers and IDs are up to date and copied somewhere secure.
• Follow instructions from local emergency managers, and evacuate if you are told to.

What should you do during a hurricane warning?

By the time a warning is issued, NWS says all preparations should be complete. Under a warning:

• Evacuate immediately if local officials order it.
• If you are staying, take refuge in a designated storm shelter or an interior room for high winds.
• If you are trapped by flooding, go to the highest level of the building, but do not climb into a closed attic, where rising water can trap you.
• Never walk, swim or drive through flood water. Ready.gov warns that six inches of fast-moving water can knock you down and one foot of moving water can sweep a vehicle away.

Keep in mind that hurricane hazards reach well beyond the coast. NWS lists inland flooding from heavy rain as the second leading cause of deaths from landfalling tropical cyclones, and tornadoes can accompany landfalling storms, typically in rain bands well away from the center.

How often does the National Hurricane Center update its alerts?

For active storms in the Atlantic and eastern Pacific, NHC issues advisory packages at least every six hours, at 5 a.m., 11 a.m., 5 p.m. and 11 p.m. Eastern time during daylight saving time. Once coastal watches or warnings are in effect, NHC adds public advisories every three hours. Each advisory lists every watch and warning in effect along with the storm’s position, strength and movement.

The familiar forecast cone shows where the storm’s center is likely to go, and NWS says the center stays inside the cone about 60 to 70 percent of the time. A storm’s effects can span hundreds of miles, and NWS notes that areas well outside the cone often experience hazards such as tornadoes or inland flooding, so check the watches and warnings for your own county rather than judging your risk by the cone alone.

How do watches and warnings relate to hurricane categories?

Hurricane watches and warnings do not depend on a storm’s category. Any hurricane, from Category 1 to Category 5, can prompt them. The Saffir-Simpson Hurricane Wind Scale rates hurricanes from 1 to 5 based only on maximum sustained wind, starting at 74 to 95 mph for Category 1, with Category 3 and higher (111 mph or more) classed as major hurricanes.

NHC stresses that the scale does not account for storm surge, rainfall flooding or tornadoes, and that hurricanes of every category can produce deadly surge and floods. The category alone does not tell you how dangerous a storm will be where you live.

How can you receive hurricane alerts?

Ready.gov recommends having several ways to get alerts. Wireless Emergency Alerts and the Emergency Alert System require no sign-up. The FEMA app can send NWS alerts for up to five locations, and you can sign up for community alerts where you live. NOAA Weather Radio and the official NHC site at hurricanes.gov carry the latest advisories, and your local NWS forecast office at weather.gov posts details for your area.

For the official wording of every tropical alert, see the National Weather Service guide to hurricane watches and warnings, and for a full preparedness checklist, visit Ready.gov’s hurricane page.

Related live coverage

When a storm threatens the U.S., follow the latest alerts, forecasts and storm updates on our U.S. Weather Live center. For live national TV coverage during major weather events, browse the networks on our Watch Live News hub.

Sources

• National Weather Service, Hurricane and Tropical Storm Watches, Warnings, Advisories and Outlooks (weather.gov)
• National Hurricane Center, Glossary of NHC Terms (nhc.noaa.gov)
• National Hurricane Center, Saffir-Simpson Hurricane Wind Scale and Tropical Cyclone Climatology (nhc.noaa.gov)
• National Weather Service, Hurricane Safety and Hurricane Hazards (weather.gov)
• Ready.gov (FEMA), Hurricanes (ready.gov)