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Understanding Typhoon Information

A typhoon's category alone cannot tell you the risk at your location. The category measures wind strength, while actual impacts also depend on storm size, movement, rainbands, terrain, and marine conditions. This guide explains how to read each item on sanCheck's typhoon card.

What is a typhoon?

In KMA and JMA usage, a tropical cyclone in the western North Pacific is treated as a typhoon when the maximum wind near its center reaches at least 17 m/s. KMA intensity uses the 10-minute mean maximum wind near the center.

Strong wind and heavy rain can occur far from the center when an area falls within the wind field or outer rainbands. Do not use the center line alone to decide whether a location is affected.

KMA's 2026 categories 1–5

Starting with the first typhoon of 2026, KMA uses numerical intensity categories 1–5 instead of the previous wording. The category is based only on maximum wind near the center.

ClassificationMaximum wind near the center
Tropical depressionUnder 17 m/s
Category 117 m/s to under 25 m/s
Category 225 m/s to under 33 m/s
Category 333 m/s to under 44 m/s
Category 444 m/s to under 54 m/s
Category 554 m/s or above

A higher number means stronger wind, but a lower-category storm can still cause major impacts if it moves slowly or produces prolonged heavy rain.

Reading the typhoon card

Central pressure

Pressure at the storm center, shown in hPa. A low central pressure by itself does not determine wind or damage; read it together with maximum wind, wind radii, and storm movement.

Maximum wind

The analyzed 10-minute mean maximum wind near the center. sanCheck's numerical category is based on this value. It is different from a short-lived gust observed at a specific location.

Gale radius · Storm radius

Gale radius describes the area with winds of at least 15 m/s; storm radius uses at least 25 m/s. Typhoons are not perfect circles, so the reach can differ by direction.

Direction · Speed

The direction and speed of the storm center. A slow-moving storm can prolong wind and rain over one area, while changing speed can shift expected arrival times.

How should the forecast track be read?

Basic checks as a typhoon approaches

Before impacts

  • Check current warnings and evacuation information.
  • Bring loose outdoor objects inside or secure them.
  • Prepare for possible power or water disruptions and keep phones charged.
  • Leave rivers, coasts, underground spaces, and other restricted risk areas when authorities advise it.

During impacts

  • Reduce unnecessary travel and stay away from windows.
  • Do not enter flooded roads or underpasses.
  • Stay away from downed wires and damaged structures.
  • Follow evacuation instructions from the responsible authorities.

Related reading

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