Terminal Aerodrome Forecast (TAF)

Definition

A TAF (Terminal Aerodrome Forecast) is an official, aviation-specific weather forecast issued for airports. It provides a concise summary of expected meteorological conditions in the vicinity of an aerodrome, typically within a 5 NM radius, over a 30-hour or 24-hour period (occasionally 9 or 12 hours for smaller airports).
TAFs are issued by meteorological authorities and are formatted according to ICAO standards for international use.

Purpose

Help pilots plan departure and arrival operations
Assist in alternate airport selection
Provide essential input for IFR fuel planning, approach minima, and contingency strategies

Format Overview

A typical TAF includes:

Airport ICAO code
Date/time of issuance
Forecast validity period
Forecasted wind, visibility, weather phenomena, cloud layers
Probability and timing of changes (e.g., TEMPO, BECMG, PROB)

Example TAF

LOWW 081100Z 0812/0918 27008KT 9999 SCT030
BECMG 0814/0816 32012KT
TEMPO 0816/0820 4000 -RA BKN020
PROB30 TEMPO 0900/0904 2000 TSRA

Decoded:

LOWW: Vienna International Airport
081100Z: Issued on the 8th day at 1100 UTC
0812/0918: Valid from the 8th at 12:00 UTC until the 9th at 18:00 UTC
27008KT: Wind from 270° at 8 knots
9999: Visibility 10 km or more
SCT030: Scattered clouds at 3000 ft
BECMG 0814/0816: Becoming between 14:00–16:00 UTC
32012KT: New wind from 320° at 12 knots
TEMPO 0816/0820: Temporary condition between 16:00–20:00 UTC
4000 -RA BKN020: Visibility 4 km, light rain, broken clouds at 2000 ft
PROB30 TEMPO 0900/0904 2000 TSRA: 30% chance of thunderstorms with rain, 2 km visibility from 00:00–04:00 on the 9th

Key TAF Elements

Code	Meaning
KT	Wind in knots
9999	Visibility 10 km or more
SCT/BKN/OVC	Cloud coverage: Scattered, Broken, Overcast
BECMG	Gradual change in weather
TEMPO	Temporary weather conditions
PROB	Probability of certain weather (e.g., PROB30 = 30%)
CB	Cumulonimbus clouds (severe weather risk)

TAF vs. METAR

Feature	TAF	METAR
Type	Forecast	Actual observation
Duration	9–30 hours	Updated every hour
Use	Planning	Real-time conditions
Format	Predictive	Snapshot

Why TAFs Matter

✅ Critical for fuel planning and alternates
✅ Used to determine landing and takeoff minima
✅ Aid in assessing weather-related delays or rerouting
✅ Required for IFR pre-flight planning

Tips for Pilots

Always compare TAF with METAR to assess trends
Monitor BECMG/TEMPO to anticipate weather windows
Use LearnATC to practice interpreting and applying TAFs to real scenarios
Check for TAF amendments (TAF AMD) that override previous forecasts