TAF Decoder
Decode a Terminal Aerodrome Forecast — validity, wind, visibility, and cloud.
Inputs
Result
Station
EGLL
Issued
28 @ 17:00Z
Valid
Day 28 18:00Z → day 29 24:00Z
Wind
From 250° at 10 kt
Visibility
10 km or more
Cloud
Scattered (3–4 oktas) at 2500 ft
Formula
Ref- Validity: ddHH/ddHH (from → to, in Z)
- Change groups: FM / BECMG / TEMPO / PROBnn
- Wind, visibility and cloud decode as in a METAR
Worked example
RefDecode: EGLL 281700Z 2818/2924 25010KT 9999 SCT025.
- 1.Issued on the 28th at 17:00Z.
- 2.Valid day 28 18:00Z to day 29 24:00Z.
- 3.Wind from 250° at 10 kt; visibility 10 km or more.
- 4.Scattered cloud at 2,500 ft.
London, valid 2818/2924, wind 250/10, 10 km+, scattered 2,500 ft.
How it works
RefA TAF forecasts aerodrome weather over a validity window, with change groups (FM, BECMG, TEMPO, PROB) marking how conditions evolve. This tool decodes the header, validity and the common weather fields, and labels each change group with its time so you can follow the sequence.
DGCA student tip
ExamTAF and METAR share the same weather codes, so learn them once. Watch the validity period carefully — a TEMPO only applies within its own window, and FM starts a brand-new set of conditions from that time.
Common mistakes
Watch- Applying a TEMPO/BECMG condition outside its stated time window.
- Reading the validity period as the issue time.
- Assuming a TAF covers the whole flight — check it spans your ETA.