TAF decoder
Turns a pasted into a timeline of forecast periods (FM, TEMPO, BECMG, PROB30/40) in plain language, with and local times, winds (true), visibility, weather, clouds and ceilings, and flight categories.
Planning and education aid. Not for primary navigation. Full disclaimer
A published result changed on 2026-09-19: Present weather now reads as the FAA Aviation Weather Handbook does, with intensity on the precipitation: +TSRA is "thunderstorm with heavy rain" (was "heavy thunderstorm rain"), +SHRA is "heavy rain showers", and VCSH is "showers in the vicinity". Tool versions 1.1.0. The METAR and winds-aloft decoders are now stable. Changelog
KDEN forecast from day 18 at 1800Z to day 19 at 1800Z, 5 periods. Get a current official briefing before flight.
| Change | From | To | From (local) | Start | Wind | Visibility | Clouds | Ceiling | Flight category | Weather |
|---|---|---|---|---|---|---|---|---|---|---|
| base | day 18 at 1800Z | day 19 at 0200Z | 12:00 local | 0.0 | 300° true at 12 kt, gusting 22 kt | more than 6 SM | scattered at 8,000 ft; broken at 20,000 ft | 20,000 ft | VFR | |
| temporary | day 18 at 2000Z | day 18 at 2400Z | 14:00 local | 2.0 | variable at 25 kt, gusting 35 kt | 3 SM | broken at 6,000 ft, cumulonimbus | 6,000 ft | MVFR | thunderstorm with rain |
| from | day 19 at 0200Z | day 19 at 1800Z | 20:00 local, previous day | 8.0 | 320° true at 8 kt | more than 6 SM | few at 10,000 ft | VFR | ||
| becoming | day 19 at 1000Z | day 19 at 1200Z | 04:00 local | 16.0 | 180° true at 10 kt | |||||
| 30% probability | day 19 at 1400Z | day 19 at 1800Z | 08:00 local | 20.0 | 3 SM | broken at 3,000 ft | 3,000 ft | MVFR | light rain showers |
- Issued
- Valid from
- Valid to
- Valid for
- Periods
- Notice
Provenance
- Computed by
- aviation.weather.taf-decode 1.2.1, core 0.1.0
- Model
- TAF coding as in the FAA Aviation Weather Handbook and FAA Order JO 7900.5E groups; day numbers below the start day belong to the next month
- Accuracy
- Decodes the text as written. It does not check the forecast against the station or fetch anything.
- Notes
- None
- Cites
- Federal Aviation Administration, Aviation Weather Handbook, FAA-H-8083-28B; Federal Aviation Administration, Surface Weather Observing, FAA Order JO 7900.5E
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: TAF coding as in the FAA Aviation Weather Handbook and FAA Order JO 7900.5E groups; day numbers below the start day belong to the next month
Accuracy: Decodes the text as written. It does not check the forecast against the station or fetch anything.
When to use this: Use this when planning around a forecast: it lays a TAF out as a timeline of periods — the base period and each FM, TEMPO, BECMG, and PROB group — in plain language, with both UTC and local times, so you can see what is forecast when you expect to arrive, and how the flight category changes across the period.
Limitations: It reads the forecast as written and does not fetch it, check it against the station, or tell you whether to go. A TAF covers a radius around the airport and is amended, so an old one in a text box stays old here. Winds are true. Probability and temporary groups describe conditions that may occur, not a sequence, and this tool shows them as the coding gives them.
Worked example: A Denver TAF valid across midnight. Source: add-practitioner-essentials TAF scenario: valid 18:00Z on the 18th to 18:00Z on the 19th, each change group placed in order.
You enter
- TAF
- TAF KDEN 181720Z 1818/1918 30012G22KT P6SM SCT080 BKN200 TEMPO 1820/1824 VRB25G35KT 3SM TSRA BKN060CB FM190200 32008KT P6SM FEW100 BECMG 1910/1912 18010KT PROB30 1914/1918 3SM -SHRA BKN030
- Local UTC offset
- -06:00
You get
- Station
- KDEN
- Issued
- day 18 at 1720Z
- Valid from
- day 18 at 1800Z
- Valid to
- day 19 at 1800Z
- Valid for
- 24 h
- Periods
- 5
- Notice
- Decoded from the text you pasted. Get a current official briefing before flight.
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.2.1, core 0.1.0. See this tool in the verification report.
Changes
- 2026-09-23, fixed: Plain-number results in a fixed unit now show that unit: the battery current reads 9.7 A where it read 9.7, and decibels, gigabytes, pulses per square meter, grams per kilogram, nautical miles per gallon, hours, nanoteslas, and minutes now carry their units too. The numbers themselves do not change. Each tool's patch version went up. Changelog
- 2026-09-19, fixed: The TAF decoder now reads the ICAO TX and TN maximum and minimum temperature groups (they were listed as not decoded) and flags a change group that falls outside the forecast's valid period instead of placing it silently (found in a live Geneva TAF). Tool version 1.2.0. It is now stable, agreeing with pytaf on 588 live TAFs and with the FAA Aviation Weather Handbook's example. Changelog
- 2026-09-19, result change: Present weather now reads as the FAA Aviation Weather Handbook does, with intensity on the precipitation: +TSRA is "thunderstorm with heavy rain" (was "heavy thunderstorm rain"), +SHRA is "heavy rain showers", and VCSH is "showers in the vicinity". Tool versions 1.1.0. The METAR and winds-aloft decoders are now stable. Changelog
Checked against: 21 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Aviation Weather Handbook, FAA-H-8083-28B, Federal Aviation Administration, FAA-H-8083-28B. Section 8.4 (altimetry), section 3.4.2.14 and tables 3-17 and 3-18 (flight categories), section 24.4 (METAR and SPECI), section 27.2 (FB winds and temperatures aloft), and section 27.4 (TAF). Read free.
- Surface Weather Observing, FAA Order JO 7900.5E, Federal Aviation Administration, JO 7900.5E Change 1. Chapter 14 (METAR/SPECI coding) and Chapter 15 (remarks: AO1/AO2, SLP, T group, PK WND, WSHFT, PRESRR/PRESFR, $).
Terms
- TAF: terminal aerodrome forecast
- A forecast for an airport, usually 24 or 30 hours long, coded like a METAR with change groups such as FM, TEMPO, BECMG, and PROB30. Source: Aviation Weather Handbook
- UTC: Coordinated Universal Time
- The world's civil time standard, kept within 0.9 s of Earth's rotation by leap seconds. Aviation calls it Zulu time, written with a Z. Source: IERS Bulletin C (leap seconds)
TAF — terminal aerodrome forecast
A forecast for an airport, usually 24 or 30 hours long, coded like a METAR with change groups such as FM, TEMPO, BECMG, and PROB30.
Source: Aviation Weather Handbook
UTC — Coordinated Universal Time
The world's civil time standard, kept within 0.9 s of Earth's rotation by leap seconds. Aviation calls it Zulu time, written with a Z.
Source: IERS Bulletin C (leap seconds)
Learn the concept: How to read a METAR, How to read a TAF