How to read a TAF

A TAF (terminal aerodrome forecast) tells you what the weather is expected to do at an airport and its immediate surroundings (roughly an 8 km radius) over the next several hours. It uses the same codes as a METAR, so if you can read one you can read the other. The new part is the time structure.

An example

TAF EGLL 011100Z 0112/0218 22012KT 9999 FEW040 BECMG 0115/0117 24018G30KT TEMPO 0116/0120 4000 SHRA BKN014CB PROB30 TEMPO 0200/0206 1500 BR

TAF	Report type. It can be followed by AMD (amended), COR (corrected) or CNL (cancelled).
EGLL	The airport.
011100Z	Issued on day 01 at 11:00 UTC.
0112/0218	Valid from day 01 at 12:00 UTC to day 02 at 18:00 UTC (30 hours).
22012KT 9999 FEW040	The starting conditions: wind from 220° at 12 kt, visibility 10 km or more, few clouds at 4,000 ft.
BECMG 0115/0117 24018G30KT	Becoming, between 15:00 and 17:00 on day 01, wind from 240° at 18 kt gusting 30 kt.
TEMPO 0116/0120 4000 SHRA BKN014CB	Temporarily, between 16:00 and 20:00, visibility 4,000 m in showers of rain with broken cumulonimbus at 1,400 ft.
PROB30 TEMPO 0200/0206 1500 BR	A 30% chance of temporary visibility 1,500 m in mist between 00:00 and 06:00 on day 02.

An illustrative forecast, not a live one.

The change groups

Group	Meaning
FM	From. A rapid change: the new conditions replace everything before them from that time on. FM011800 means from day 01 at 18:00 UTC.
BECMG	Becoming. A gradual change that is complete by the end of the stated period, after which the new conditions persist.
TEMPO	Temporarily. Short fluctuations, each lasting under an hour and together covering less than half of the period. The earlier conditions are the baseline.
PROB30 / PROB40	A 30% or 40% probability of the conditions that follow, often combined with TEMPO.

Reading a TAF in practice

Check the validity period first. A TAF only covers the hours it states, and it is usually reissued every 3 to 6 hours.
Read the base conditions at the start.
Walk forward through the groups in time order. Apply FM as a replacement, BECMG as a gradual change and TEMPO or PROB as possible short-lived worsening.
Look at the worst case, not just the base. A TEMPO with thunderstorms or low cloud matters if you plan to arrive during that window.
Compare with the latest METAR. If reality has drifted away from the forecast, trust the observation.

Other useful terms: NSW (no significant weather), CAVOK (see the abbreviation list) and NIL (no forecast available). Not every airport issues a TAF; many small airfields only have a METAR, or neither.

Not sure how a TAF differs from a METAR or a SPECI? See METAR vs TAF vs SPECI.

See real reports: EGLL · KJFK · EDDF · EPWR · all airports.

Educational material. It does not replace flight training or an official weather briefing.