TAF Decoder — Decode Aviation Forecasts Instantly
Paste a raw Terminal Aerodrome Forecast or enter any ICAO airport code to translate it into plain English. Every change group — FM, BECMG, TEMPO, INTER, PROB30/PROB40 — is decoded with its validity window so you can read a 30-hour forecast in seconds.
Popular airports: KJFK (New York), EGLL (London Heathrow), VIDP (Delhi), KLAX (Los Angeles), KORD (Chicago O'Hare), YSSY (Sydney), VHHH (Hong Kong), OMDB (Dubai), EHAM (Amsterdam), VABB (Mumbai)
Enter an airport ICAO code or paste a raw TAF string above to begin.
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Worked examples — read three real TAFs
Three TAFs of progressively increasing complexity, decoded in full. Hover any chip to see what it means.
A standard JFK forecast. Begins with surface conditions, then steps through three FM groups as the day evolves — wind veers and freshens, then a layer of broken cloud builds in the afternoon.
Forecast timeline
Day 1 18:00Z – day 2 24:00Z
Wind from the west at 15 kt gusting 25, visibility 6+ miles, scattered clouds at 4,000 ft.
From day 2, 01:00Z
Wind from the west at 12 kt, visibility 6+ miles, scattered clouds at 5,000 ft.
From day 2, 12:00Z
Wind from the west at 10 kt, visibility 4 miles, light showers of rain, overcast clouds at 2,000 ft.
From day 2, 18:00Z
Wind from the west-northwest at 15 kt, visibility 6+ miles, broken clouds at 3,000 ft.
A more complex Heathrow forecast with a TEMPO degradation and a 30% probability of thunderstorms in the early afternoon. Useful to study how transient hazards are encoded without changing the base forecast.
Forecast timeline
Day 1 18:00Z – day 2 24:00Z
Wind from the west-southwest at 18 kt, visibility 10+ km, scattered clouds at 2,500 ft.
Day 1 18:00Z – day 1 21:00Z
Wind from the west-southwest at 22 kt gusting 34.
Day 2 02:00Z – day 2 08:00Z
Visibility 4000 m, light rain, broken clouds at 1,200 ft.
Day 2 12:00Z – day 2 16:00Z
Visibility 1500 m, thunderstorm with rain, broken clouds at 800 ft.
Indira Gandhi International on a January morning. The TAF starts in low-IFR conditions and forecasts a gradual BECMG transition as the fog burns off. Pilots arriving at dawn need to know whether their approach minima will be met by the time they land.
Forecast timeline
Day 1 06:00Z – day 2 12:00Z
Variable wind at 2 kt, visibility 500 m, fog.
Day 1 07:00Z – day 1 09:00Z
Wind from the south at 5 kt, visibility 1500 m, mist, broken clouds at 800 ft.
Day 1 10:00Z – day 1 13:00Z
Wind from the southwest at 8 kt, visibility 5000 m, clear skies / no significant cloud.
From day 1, 15:00Z
Wind from the southwest at 10 kt, CAVOK (visibility 10+ km, no significant cloud).
How to read a TAF — step by step
A TAF is just a sequence of fields, each in a fixed position. Walk through them in order and the report decodes itself.
- 1
Report Type (TAF)
Most TAFs begin with the literal token TAF (and optionally AMD for amended or COR for corrected). It tells you the message that follows is a forecast, not a current observation like a METAR.
- 2
Station ID
The 4-letter ICAO code of the airport the forecast applies to, for example KJFK for John F. Kennedy International or VIDP for Indira Gandhi International, Delhi.
- 3
Issue Time (DDHHMMZ)
The day-of-month, hour and minute the TAF was issued, in Zulu (UTC). Always convert to your local time when comparing against your departure or arrival time.
- 4
Validity Period (DDHH/DDHH)
The window the forecast covers. Most TAFs are valid for 24 or 30 hours. Read it as 'from day-DD hour-HH until day-DD hour-HH', all UTC. A TAF expires the moment its end-time passes.
- 5
Initial Conditions
Right after the validity window, the forecaster lists the surface conditions expected from the start of the period: wind, visibility, weather phenomena, cloud layers. These hold until the first change group.
- 6
FM (From) Groups
FM-DD-HH-MM means 'from this exact moment, conditions become as listed'. FM groups describe an instantaneous, complete change to the forecast — a new wind, a new visibility, a new cloud picture. They replace the previous group entirely.
- 7
BECMG (Becoming) Groups
BECMG-DDHH/DDHH describes a gradual change to the listed conditions over the window. By the end of the window the new conditions hold; before the start of the window the previous conditions still apply.
- 8
TEMPO and INTER Groups
TEMPO means temporary fluctuations expected to last under an hour at a time and for less than half the period. INTER (used in some regions) means more frequent intermittent fluctuations. Either way, the base forecast still applies; these are short-lived deviations.
- 9
PROB30 / PROB40 Groups
Probability groups quote a 30% or 40% chance of the listed conditions during the window. PROB30 TEMPO means '30% chance of these temporary fluctuations'. They are uncertainty markers — plan for them, but do not assume they will occur.
Change groups at a glance
Every forecast period in a TAF carries one of these markers. The colour matches the badge used in the decoder above.
Conditions change instantaneously to those listed
Gradual change to the listed conditions during the window
Conditions occur intermittently for less than half the period
Frequent intermittent fluctuations during the window
30% probability of the listed conditions during the window
40% probability of the listed conditions during the window
30% probability of temporary fluctuations during the window
40% probability of temporary fluctuations during the window
Frequently asked questions
Related tools
TAFs forecast what the airport will be doing. METARs report what it's doing right now. Pilots typically read both side-by-side when planning.
Open the METAR Decoder