Aviation weather

How aviation weather reporting fits together

Aviation weather runs on a small family of coded products, and two of them cover most of a light-aviation briefing. The METAR is the observation: an automated station or an observer measures wind, visibility, present weather, cloud, temperature and pressure at the field and publishes the result at least hourly in a fixed international format. The TAF is the forecast: a meteorologist writes what the aerodrome area is expected to do over the next 24 to 30 hours, in the same coding, and amends it whenever reality moves away from the script.

The craft is in reading them together. The METAR tells you whether the field is usable now; the trend of successive METARs tells you which way conditions are moving; and the TAF tells you what to expect at your arrival time and whether an alternate needs to be real or just paperwork. Every station page on this site puts the two side by side, decodes them field by field, and works out the flight rules category so a falling ceiling is visible at a glance.

Learn the codes once, read every airport forever

The format is the same from Madrid to Mombasa — that is its whole point. Twenty minutes with the decoder and a handful of raw reports from airports you know is enough to stop translating and start reading. From there, the station lookup covers roughly 5,200 reporting airports worldwide, each with the current report, the forecast and the airfield reference data one click away.

The pressure line matters more than it looks

One habit separates tidy altimetry from altitude busts: take the QNH from the METAR every time, even when it looks unchanged. A single hectopascal is roughly 28 feet, and pressure falling behind a front can move faster than the hourly reports suggest. The old rule condenses it: from high to low, look out below. The decoded view on every station page pulls the QNH out of the raw line so it cannot hide between cloud groups.

Frequently asked questions