How to Read a TAF: Aviation Forecasts Explained
Understand how an airport forecast expresses validity, expected conditions and changes over time.
Illustrative airport forecast context. A TAF is a time-bounded forecast product, not a photograph of future conditions.
What is a TAF?
A Terminal Aerodrome Forecast describes expected meteorological conditions at an airport during a stated validity period. It is issued and amended by an authorized meteorological service and should always be interpreted with its timestamp, validity and change groups.
How TAF differs from METAR
A METAR is an observation. A TAF is a forecast. The current observation can differ from the forecast, and a later amendment can supersede an earlier TAF.
Anatomy of a TAF
TAFKJFK281130Z2812/291818012KTP6SMSCT020 BKN040TEMPO 2814/2818 3SM TSRAWorked syntax example only — not a current forecast.
Airport identifier
KJFK identifies the airport for which the terminal forecast is issued.
Issue time
281130Z means the forecast was issued on day 28 at 11:30 UTC.
Validity period
2812/2918 covers day 28 at 12:00 UTC through day 29 at 18:00 UTC.
Wind
18012KT describes expected wind from 180 degrees at 12 knots.
Visibility
P6SM means visibility greater than six statute miles in this reporting convention.
Clouds and ceiling
Cloud groups use the same coverage abbreviations seen in METAR. Broken and overcast layers may establish the forecast ceiling.
Weather phenomena
Forecast weather codes describe expected precipitation, thunderstorms, obscuration and other relevant phenomena.
Forecast change groups
Change groups define when a different set of conditions is expected. Their time window is part of the meaning.
TEMPO
TEMPO describes temporary fluctuations expected during the stated sub-period.
BECMG
BECMG indicates conditions forecast to become a new prevailing state during a period.
PROB
PROB30 or PROB40, where used, expresses an assigned probability for the following conditions. Regional rules differ.
TAF example decoded
| Group | Meaning |
|---|---|
| 281130Z | Issued day 28 at 11:30 UTC |
| 2812/2918 | Valid day 28 12:00 through day 29 18:00 UTC |
| 18012KT P6SM | Wind and prevailing visibility |
| SCT020 BKN040 | Forecast cloud layers |
| TEMPO … TSRA | Temporary thunderstorm and rain conditions in the stated period |
From evidence to the PlanetVexa view
Each stage changes what can be claimed. PlanetVexa keeps the source record, derived interpretation and visual presentation visibly distinct.
- 01Observations and guidance
Current reports, atmospheric analysis and forecast guidance establish the starting context.
- 02Forecaster product
An authorized service issues a TAF with validity and change groups.
- 03Source normalization
PlanetVexa preserves the raw forecast and separates its time periods.
- 04Airport page
Issue time, validity, decoded periods and amendments remain visible together.
Informational context, not operational instruction
PlanetVexa presents source-backed reports and forecasts for education and planetary context. Decoding is not a substitute for certified training, official briefing products, current charts, notices, procedures or decisions by qualified aviation personnel. Source values can be corrected or amended.
Connected live aviation weather comes from the NOAA Aviation Weather Center. Airport metadata, runways and frequencies come from OurAirports open data; frequencies must be confirmed with an official operational source before use.
Explore a Real Airport Forecast
These are current backend records when available. Missing source data is shown as unavailable rather than replaced with a demonstration value.
TAF KJFK 141138Z 1412/1518 25012KT P6SM FEW250 FM141500 27012G18KT P6SM FEW040 SCT250 FM142000 28012G18KT P6SM SCT050…
GRU · SBGRSão Paulo/Guarulhos–Governor André Franco Montoro International AirportTAF SBGR 140900Z 1412/1518 31007KT 9999 SCT045 TX27/1416Z TN18/1506Z BECMG 1416/1418 TS BKN040 FEW045CB BECMG 1418/1420…
LHR · EGLLLondon Heathrow AirportTAF EGLL 141053Z 1412/1518 21012KT 9999 SCT035 TEMPO 1503/1512 BKN012 PROB30 TEMPO 1503/1506 8000 -RA PROB40…
FAQ
How long is a TAF valid?
The validity group in the TAF states its exact window. Duration varies by product and airport.
Does TEMPO replace the entire forecast?
No. It describes temporary conditions during a specific sub-period within the forecast.
Can a TAF be amended?
Yes. Always check issue time and amendment status against the responsible official source.
Read the official material
Definitions and operational context are checked against the responsible institutions. External material can be revised independently of PlanetVexa.