TAF Timeline Visualizer
Real TAF where supported or training examples on an interactive timeline: FM, TEMPO and probability groups, conditions at a selected time.
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Enter an airport identifier (for example KJFK) and press Get TAF: the current terminal aerodrome forecast comes from the NOAA / National Weather Service Aviation Weather Center through this site's server, labelled LIVE (or CACHED COPY when only an older stored forecast could be served) with its issue time, when it was retrieved and whether it is valid now. Training examples (SIMULATED) are the FAA publications' TAF examples and constructed ones; a pasted TAF is PASTED.
Read the timeline from left to right. The top lane is the prevailing forecast: the initial group, then each FM group, which replaces everything before it until the next FM. BECMG (used outside the U.S.) is hatched: the change happens at an unknown time inside that period. TEMPO, PROB30 and PROB40 groups sit in their own lanes below: they are possibilities laid over the prevailing forecast, not a new forecast — the elements they do not mention carry over. The category band shows the prevailing flight category; the thin line under it the worst category a TEMPO or PROB group allows for.
Drag the cyan cursor, tap the timeline, use the arrow keys on the cursor or the slider to choose a time. The readout and the drawing then say what prevails, what is changing, what may happen (with its probability) and the flight category of each. Practice asks five questions on the forecast on screen (or a training example) and scores them; the answers stay hidden until you choose.
Assumption and limits: educational use only — not for flight planning; before flight use an official weather briefing. Live TAFs come from the Aviation Weather Center through this site's server, which keeps a copy for 10 minutes to stay within the provider's limits; a stored copy up to six hours old is shown, labelled CACHED COPY, only if the Aviation Weather Center cannot be reached. A TAF codes only the day of the month and the hour: live forecasts are placed by their issue time, training examples in a fixed month, pasted ones in the current month. The probability and category drawing, the colours (VFR green, MVFR cyan, IFR coral, LIFR purple) and the practice scoring are platform conventions. The NWS uses only PROB30 and no BECMG; both are decoded for international TAFs as the AIM describes them.
Decoding follows the Aviation Weather Handbook FAA-H-8083-28B (2026), section 27.4 (the table of contents numbers it 27.3): report type TAF / TAF AMD / TAF COR, location, issuance time, valid period ("24" is midnight at the end of the day), wind (VRB, gusts, calm), visibility (P6SM, fractions), significant weather or NSW, sky condition (SKC, layers with CB, vertical visibility), non-convective low-level wind shear (WS), and the change groups FM (self-contained new prevailing conditions), TEMPO (temporary fluctuations: more than 50 % probability, about an hour or less each time, in total less than half the period) and PROB30, with NWS Instruction 10-813 (30 October 2024) for the NWS rules and the international terms not used in NWS TAFs (CAVOK, NSC, BECMG, PROB with TEMPO) and AIM 7-1-28 / 7-1-29 for PROB40 and BECMG ("The gradual change will occur at an unspecified time within this time period. Only the changing forecast meteorological conditions are included in BECMG groups. The omitted conditions are carried over from the previous time group." - AIM 7-1-29).
Conditions at a time: the prevailing group in force (the initial group until the first FM, then the latest FM); BECMG groups completed before that time applied element by element, a BECMG in progress shown as a change, not as fact; every TEMPO / PROB group active at that time applied over the prevailing conditions as a separate possibility (its sky group replaces the whole sky, NSW ends the weather only, everything it does not give carries over). Flight categories per AIM 7-1-7 for the prevailing forecast and for each possibility.
Live data: the Aviation Weather Center Data API (aviationweather.gov/data/api) through this site's server (TAF copies 10 minutes; requests limited per visitor and for the whole site well below the provider's 100 a minute). The decoder was checked against the Aviation Weather Center's own decoding of real TAFs: the start and end of every group, its change indicator and probability, wind, visibility, weather and sky agreed in every case.
- FAA-H-8083-28B Aviation Weather Handbook (2026), 27.4 Terminal Aerodrome Forecast (TAF): 27.4.2.1-27.4.2.10 (report type, location, issuance, valid period, wind, visibility, significant weather and NSW, vicinity, cloud and vertical obscuration groups, CB, non-convective low-level wind shear, FM, TEMPO and PROB30 groups, joint-use airports), 27.4.3 (decoded examples), 27.4.4 (issuance, AMD NOT SKED, NIL TAF)
- NWS Instruction 10-813, Terminal Aerodrome Forecasts (30 October 2024): the TAF code (appendix B, PROB30 rules: no longer barred from the first nine hours), international terms not used in NWS TAFs (appendix E: CAVOK, NSC, BECMG, PROB with TEMPO)
- Aeronautical Information Manual (effective 9 July 2026) 7-1-7 (categorical ceiling and visibility conditions), 7-1-28 (key to the TAF and METAR: FM, TEMPO, PROB30 / PROB40, BECMG), 7-1-29 (TAF format, PROB30 / PROB40, BECMG, TEMPO, NSW; examples)
- NOAA / National Weather Service Aviation Weather Center Data API (aviationweather.gov/data/api, read 2026-10-16): current TAFs; 100 requests per minute, a custom user agent requested, no cross-origin access; NWS information is in the public domain (weather.gov disclaimer)
- Model choices of this tool (stated on the page): the timeline drawing (possibilities in their own lanes, BECMG hatched), category colours, placing day / hour stamps in a month (issue time, a fixed month for examples, the current month for pasted text), practice questions and scoring, training examples from the FAA publications or constructed (identifiers beginning with X)