Taiwan Sea vs Land Typhoon Warning: When Issued and Lifted

The sea typhoon warning looks at the "sea" and the land typhoon warning looks at the "land," and both are based on the typhoon's force-7 wind radius (7 級風暴風範圍). The Central Weather Administration (CWA) issues the sea warning 24 hours before the force-7 wind area is forecast to possibly reach waters within 100 km of Taiwan's main island or of Penghu, Kinmen or Matsu; it issues the land warning 18 hours before the area is forecast to possibly reach land. A warning is also lifted based on whether the force-7 wind area has left the waters or the land.

Note: Typhoon warnings are issued by the CWA, while work and school closures (the typhoon day-off announcement, 停班停課) are decided by the head of each county or city; a land warning does not mean a day off. During a sea warning, do not go to the shore to play in the water or take part in activities; this reminder is written plainly in question 3 of the CWA FAQ. For actual wind and rain, rely on the CWA's latest warning bulletin and wind and rain forecasts.

Conditions for issuing sea and land warnings

Question 88 of the CWA's "100 typhoon questions" (颱風百問) sets out the standard for issuing typhoon warnings in the Taiwan area, summarized below. The "force-7 wind radius" in the table is, according to question 13, the distance from the typhoon center out to where average wind speed is 14 meters per second (the lower limit of force-7 wind speed), that is, the area covered by the storm radius.

Question 88 adds a few points: when a sea warning is issued, if the force-7 wind area is forecast to possibly reach land on Green Island or Orchid Island (Lanyu), they are included in the warning area; when a typhoon forms in the waters near Taiwan, or its storm radius, speed or direction changes in a special way, a sea or land warning can be issued directly, and both at the same time if necessary; when a typhoon turns away or dissipates, the warning can be lifted directly.

So "sea warning first, land warning a few hours later" is the usual pattern, not a rule. Sometimes a typhoon moves fast and a land warning follows a few hours after the sea warning; sometimes a typhoon circles offshore and the sea warning stays up for two days with no land warning. To see when your area will enter the storm circle (暴風圈), check the storm circle and warning areas on Taiwan real-time typhoon track and warnings.

How to read the numbers on a warning bulletin

The CWA typhoon warning bulletin (question 89) always contains the fields below; understanding a few of them is enough.

• Typhoon number and report number: which typhoon warning of the year it is, and which report this is. The higher the report number, the longer the warning has been running.
• Typhoon intensity: divided into three levels, weak, moderate and strong, by the maximum average wind speed near the center; see the table below.
• Storm radius: the distance from the typhoon center out to where average wind speed is 14 meters per second (force 7), and the distance out to 25 meters per second (force 10). Warnings are issued and lifted on the force-7 storm radius.
• Maximum wind near the center: the 10-minute average wind speed, given in meters per second and the equivalent wind force.
• Maximum instantaneous gust: the instantaneous maximum gust in meters per second and the equivalent wind force. The work and class suspension measures themselves do not define gusts; this article reads the measures' "force-10 gusts" as corresponding to this instantaneous value.
• Warning areas and matters: the areas under a land warning, a sea warning and a rainfall alert, listing the stations that have already seen heavier wind and rain.
• Scheduled time of the next warning.

Intensity and storm radius are two different things. Question 13 says typhoon storm radii average about 200 to 300 km, and large ones can reach 400 to 500 km; question 14 says stronger typhoons usually also have larger storm areas, but not always, and sometimes the radius is not large while the intensity is not weak. As an example from this article: the storm circle of a weak typhoon can also sweep across all of Taiwan, and a moderate typhoon can also just brush the Hengchun Peninsula. For how strong each wind force actually is, see How strong are force-7 winds and force-10 gusts.

What the strike probability means

Several days before a warning is issued, the CWA typhoon news page first provides the "typhoon storm strike probability": in 6-hour periods, it shows the probability that each major city and outlying island will be hit by the typhoon's force-7 storm circle within the next 120 hours. The CWA explains this number as follows.

• What 80% means: out of 100 cases in the past five years where the CWA officially forecast a similar track, there were 80 cases where the typhoon's force-7 winds hit that place.
• A high probability does not mean heavy wind and rain: as a typhoon approaches the probability usually rises and wind and rain strengthen, but because of the typhoon's asymmetric structure and terrain, wind and rain differ from place to place, so you cannot judge entirely by the probability value; look at the wind and rain forecasts.
• Probabilities cannot be added: a single 6-hour probability will not be larger than the 120-hour probability, and the 120-hour probability is not the sum of the periods.
• What it does not tell you: the CWA states explicitly that the probability product does not directly or indirectly indicate the probability of the typhoon center making landfall, the size of disasters and their probability of occurring, or the timing of typhoon warnings.

The CWA also advises reading the "possible / earliest possible arrival time of typhoon winds" together with the strike probability color scale, because looking at the arrival time alone overestimates the risk; and once a warning is issued, for the next 24 hours rely instead on the more frequently updated products: the warning bulletin, wind and rain forecasts and weather advisories.

What to do at home during sea and land warnings

The following home sequence is compiled by this article according to the warning timeline, not an official rule.

FAQ

Does a land typhoon warning always mean a typhoon day off?

Not necessarily. The typhoon warning is issued by the CWA according to whether the force-7 wind area will hit land; work and class suspension is decided by the head of each county or city under the natural-disaster work and class suspension measures (天然災害停止上班及上課作業辦法), whose threshold is average wind of force 7 or gusts of force 10 in areas the storm radius may pass within 4 hours, or 24-hour rainfall reaching each county or city's alert value. When a land warning covers all of Taiwan, it is common for counties and cities with little wind and rain to carry on working as usual.

Can I go to the shore to watch the waves during a sea warning?

No. Question 3 of the CWA FAQ states that during a sea warning the public should avoid going to the shore to play in the water or take part in activities, to guard against accidents caused by long swells. One purpose of the sea warning is to give boats within 100 km offshore 24 hours to get into port.

What does a bulletin saying "force-7 storm radius 150 km" mean?

Within 150 km outward from the typhoon center, average wind speed reaches 14 meters per second (force 7) or more. The bulletin also gives a storm radius for force-10 wind (25 meters per second), which is smaller in area and stronger in wind. When your home is closer to the typhoon center than the force-7 storm radius, you are inside the storm circle.

Can it still rain heavily after the land warning is lifted?

Yes, it can. The condition for lifting a land warning looks only at whether the force-7 wind area has left land, not at rain. The typhoon's outer circulation or a southwest airflow it draws in may still bring heavy rain after the warning is lifted, and the CWA will then remind people with a heavy rain or extremely heavy rain advisory; also see Rainfall levels and advisories.

Last updated: 2026-10-30

This article is compiled by SOSfix editors from public information and is for general reference only; for your own case, contact the Central Weather Administration or the disaster response center of your county or city.

Sources

• CWA "100 typhoon questions" (颱風百問): Q88, "What is the standard for issuing typhoon warnings in the Taiwan area?" (checked 2026-10-30) (in Chinese): sea warning 100 km and 24 hours, land warning 18 hours, issued every 3 hours, lifting conditions, rules for Green Island and Orchid Island and for special changes.
• CWA FAQ: Q3, "When is a sea typhoon warning issued?" (in Chinese): the reason for the sea warning timing, and the reminder not to take part in activities at the shore.
• CWA FAQ: Q4, "When is a land typhoon warning issued?" (in Chinese): land warning 18 hours ahead, issued every 3 hours with the latest position added every hour.
• CWA "100 typhoon questions": Q89, "What does a typhoon warning issued by the CWA contain?" (in Chinese): the bulletin fields, force-7 (14 meters per second) and force-10 (25 meters per second) storm radii, 10-minute average wind speed and instantaneous gusts.
• CWA "100 typhoon questions": Q18, "How is typhoon intensity classified?" (in Chinese): wind speeds and wind forces of weak, moderate and strong typhoons.
• CWA "100 typhoon questions": Q13, "How is the storm area of a typhoon determined?" and Q14, "Is a typhoon's strength proportional to the size of its storm area?" (in Chinese): the definition of storm radius, the average of 200 to 300 km, and that intensity and extent are not proportional.
• CWA typhoon news: explanation of the typhoon storm strike probability (checked 2026-10-30) (in Chinese): 120 hours, probability every 6 hours, the meaning of 80%, the relation between probability and wind and rain, what the probability product does not indicate, advice on using arrival times.
• CWA product description document: information on typhoon warning bulletins (last modified 2026/01/06, PDF) (in Chinese): definitions of the timing of sea and land warnings; the update frequency is worded as every 3 hours during a sea warning and once an hour during a land warning ("updated every 3/1 hours").