How to read a TAF
A terminal aerodrome forecast (TAF) is a forecast for the weather at an airport, usually for 24 or 30 hours. After the station, issue time, and valid period (1006/1112 means from the 10th at 06:00 Z until the 11th at 12:00 Z), the first weather group is the prevailing forecast. Later groups modify it.
- FMddhhmm — from this exact time the previous prevailing forecast is replaced. A new wind, visibility, and sky become the forecast to fly on.
- TEMPO period — temporary fluctuations expected for less than half of the period. Between those times the prevailing group still applies whenever the TEMPO is not occurring.
- BECMG period — a gradual change expected sometime during the window; afterward the new condition is prevailing.
- PROB30 or PROB40 — a 30 or 40 percent chance of the stated condition, often written as
PROB30 TEMPO.
Wind, visibility, weather, and sky tokens use the same rules as a METAR — including P6SM, CAVOK, and gusts. Open the METAR decoder if you want a current observation decoded the same way.
Worked example
The KLAX sample on this page is valid from the 10th at 06:00 Z to the 11th at 12:00 Z. It starts VFR with a 250° wind at 8 kt and greater than 6 SM. From 10:00 Z the wind shifts to 230° at 12 kt. Temporarily between 16:00 and 20:00 Z, expect 5 SM, light showers, and a 1,500 ft broken ceiling (MVFR), gusting to 25 kt. From the 11th at 02:00 Z the forecast returns to clear skies and a lighter wind.
How to use it
- Copy a TAF from an official source and paste it into the box.
- Read the station, valid period, and each group in order, including the flight category on that group.
- Plan to the prevailing forecast, and treat TEMPO and PROB groups as conditions you may have to fly in or wait out — not as a promise that they will or will not occur.
Frequently asked questions
How do I read a TAF?
A TAF starts with the station, issue time, and valid period, then a prevailing condition (wind, visibility, weather, sky). Change groups follow: FM (from) is a rapid, lasting change to a new prevailing forecast; TEMPO is a temporary fluctuation for less than half the stated period; BECMG is a gradual change across a window; PROB30 or PROB40 is a 30 or 40 percent chance of a condition, sometimes combined with TEMPO.
What is the difference between FM, TEMPO, and BECMG?
FM replaces the previous prevailing forecast at a precise time. TEMPO describes conditions expected to last less than half of the period and not to replace the prevailing forecast. BECMG means the change is expected to occur gradually between the two times, after which the new condition is prevailing.
Does each TAF group get its own flight category?
Yes. Ceiling and visibility in that group are scored with the same FAA AIM thresholds used by the METAR decoder (LIFR, IFR, MVFR, VFR), and the more restrictive of the two wins. A TEMPO or PROB group can put a VFR forecast into IFR for part of the period.
Can I paste a METAR here too?
Use the METAR decoder for observations. This page looks for TAF change groups and a valid period. You can open the companion METAR decoder from the explainer below.