Weather glossary

Short definitions for the terms we use across the site.

WMO code

A two-digit number from the World Meteorological Organization table that names a weather state — clear, partly cloudy, drizzle, freezing rain, thunderstorm with hail, and so on. Models output the code; we translate it to the icons you see.

UV index

A scale from 0 to 11+ that estimates the strength of sunburn-causing radiation. WHO guidance: above 3 wear sunscreen, above 8 limit midday exposure.

Dew point

The temperature to which air must cool to become saturated. Above 18 °C feels muggy; above 21 °C is oppressive.

Apparent temperature

What it feels like when you account for humidity (summer) or wind (winter). Often called "feels-like".

Gust

A short burst of wind, typically several seconds, that exceeds the running average. Important for sailing, cycling, paragliding.

Precipitation probability

The chance that measurable precipitation (≥0.1 mm) falls at the location during the hour. 50% doesn't mean half the day — it means roughly even odds for that hour.