Paste a raw TAF (terminal aerodrome forecast) and see it as a color-coded timeline and plain-English change groups. Every FM, BECMG, TEMPO and PROB group is decoded with wind, visibility, weather, clouds, ceiling and a VFR, MVFR, IFR or LIFR flight category, plus an hour-by-hour table.
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How to use the TAF Decoder
Paste a raw TAF into the box, for example from aviationweather.gov or a flight planning app. Line breaks and indentation are fine, and several TAFs can be pasted at once.
Press Decode TAF (or just wait a moment; it decodes as you type).
Scan the timeline: the top row is the prevailing forecast, and striped rows below show temporary, probable or transition periods, colored by flight category.
Read the change group cards for wind, visibility, weather, clouds and ceiling in plain English, and use the hour-by-hour table to check a specific arrival time.
Switch between UTC and Local times, then copy the decoded text for your notes or briefing.
Anatomy of a TAF
Take TAF KJFK 211720Z 2118/2224 31012G20KT P6SM FEW050 FM212300 30008KT P6SM SKC TEMPO 2208/2212 2SM BR BKN006. The header comes first, then the initial conditions, then any number of change groups:
Group
Example
Meaning
Type
TAF, TAF AMD, TAF COR
Routine, amended or corrected forecast
Station
KJFK
ICAO airport code
Issue time
211720Z
Issued on the 21st at 17:20 UTC
Valid period
2118/2224
From the 21st 18:00 to the 22nd 24:00 UTC
Wind
31012G20KT
From 310° true at 12 kt, gusts 20 kt; VRB03KT = variable 3 kt
Visibility
P6SM / 9999 / 2SM
Over 6 statute miles / 10 km or more / 2 miles
Weather
-RA, +TSRA, BR, NSW
Light rain, heavy thunderstorm with rain, mist, no significant weather
Clouds
FEW050, BKN006, VV002
Few at 5,000 ft, broken at 600 ft (a ceiling), sky obscured with 200 ft vertical visibility
Wind shear
WS020/24045KT
Low-level wind shear: wind at 2,000 ft from 240° at 45 kt
Temperatures
TX19/2214Z TN10/2205Z
Max 19 °C at 14Z on the 22nd, min 10 °C at 05Z
Change groups compared
Indicator
What changes
How long
On the timeline
FM221500
Everything, quickly, at 15:00 UTC on the 22nd
Until the next FM or the end
New block in the prevailing row
BECMG 2201/2204
Only the listed elements, gradually during 01–04Z
Permanent afterwards
Striped transition, then a new prevailing block
TEMPO 2204/2209
Listed elements, in short spells under an hour
Less than half of the period in total
Striped overlay row
PROB30 2220/2224
Listed elements, 30% chance
During the period
Striped overlay row
PROB40 TEMPO
40% chance of temporary fluctuations
Short spells
Striped overlay row
Tips for reading TAFs
Plan for the worst of the prevailing and the TEMPO/PROB conditions around your arrival time; many operators require alternates based on them.
A TEMPO or BECMG group only changes what it lists. If a TEMPO gives only 3SM BR, the wind and clouds from the prevailing forecast still apply.
Compare the TAF with the latest METAR from the same airport (see the METAR decoder) to judge whether the forecast is running ahead or behind reality.
An amended TAF (AMD) replaces the earlier one; always use the newest issue time.
Frequently asked questions
What is a TAF?
A TAF (Terminal Aerodrome Forecast) is an aviation weather forecast for the area within about 5 statute miles of an airport. It is usually issued four times a day and covers 24 or 30 hours, describing expected wind, visibility, weather and cloud, and when they change.
What is the difference between FM, BECMG and TEMPO?
FM (from) marks a rapid, complete change: all conditions after that time are replaced. BECMG (becoming) is a gradual change of only the listed elements at some time during the given period. TEMPO (temporarily) describes fluctuations that each last less than an hour and in total cover less than half of the period, after which the prevailing conditions return.
What do PROB30 and PROB40 mean?
They give a 30% or 40% probability that the listed conditions will occur during the period. PROB30 TEMPO combines the two: a 30% chance of temporary fluctuations. In US TAFs PROB30 is used, typically for thunderstorms or precipitation, and not in the first 9 hours of the forecast.
How are the flight categories worked out?
The decoder uses the FAA thresholds with the ceiling (lowest broken, overcast or vertical-visibility layer) and visibility. VFR: ceiling above 3,000 ft and visibility above 5 miles. MVFR: ceiling 1,000–3,000 ft or visibility 3–5 miles. IFR: ceiling 500 to below 1,000 ft or visibility 1 to below 3 miles. LIFR: ceiling below 500 ft or visibility below 1 mile.
Are TAF times in local time?
No. All TAF times are UTC (Zulu). The group 2118/2224 means valid from the 21st at 18:00 UTC to the 22nd at 24:00 UTC (midnight). Use the Local button to see the same times in your device's time zone.
What does P6SM or 9999 mean?
P6SM means visibility greater than 6 statute miles, the highest value used in US TAFs. 9999 is the international equivalent, meaning 10 kilometers or more. CAVOK goes further: visibility 10 km or more, no cloud below 5,000 ft, no cumulonimbus and no significant weather.
Can I use this for flight planning?
It is a learning and convenience tool. Always get an official weather briefing and read the original TAF before flying. Unusual regional groups are shown as not recognized rather than guessed.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.