How Are Windstorm Wind Speeds Rated?

Storm reports rate wind events on scales, and the numbers mean less than they seem to unless you know what each scale measures. The two things most often confused: ratings assigned after a storm based on damage, and alerts issued before or during a storm based on forecasts.

The EF scale: tornadoes, rated by damage

Tornado intensity is rated on the Enhanced Fujita (EF) scale, from EF0 to EF5. The key fact, explained on the National Weather Service's EF scale reference, is that the rating is assigned by surveying damage, not by measuring wind directly: surveyors examine what happened to buildings, trees, and other indicators, and work backward to an estimated wind speed range. Per that reference, the estimated three-second-gust ranges run from 65–85 mph at EF0 up to over 200 mph at EF5.

Two consequences for reading reports:

• An EF rating is an estimate from evidence, so a tornado over open fields may be rated lower than its true winds simply because it hit little worth surveying.
• The rating describes the tornado's most intense damage, not what every structure in its path experienced.

Straight-line winds

Most wind damage in Texas does not come from tornadoes. Severe thunderstorms produce damaging straight-line winds, and hurricanes and tropical storms produce sustained high winds over large areas. The NWS wind safety page covers these high-wind hazards and how they differ. After a storm, surveyors often have to determine whether damage came from a tornado or straight-line winds — the debris patterns differ — which is why early reports sometimes change.

Hurricanes carry their own category ratings on a separate scale (the Saffir-Simpson scale), based on sustained wind speed rather than surveyed damage — a different logic from the EF scale.

Watches and warnings are not ratings

A watch means conditions are favorable for a hazard; a warning means the hazard is occurring or imminent. The NWS wind safety page defines its wind watch and warning products. These are forecasts and alerts, not measurements — a high wind warning tells you what is expected, while an EF rating tells you what a survey later concluded.

Why this matters for property owners

Wind ratings show up in contexts that touch homeowners directly: news coverage of a storm that hit your area, post-event survey reports, and discussions of how buildings performed. Knowing that an EF number is a damage-derived estimate, and that a warning is a forecast product, keeps those documents readable. For how buildings are made to resist the winds these scales describe, see wind retrofit basics.