A TAF (Terminal Aerodrome Forecast) is an official weather forecast issued for the airspace around a specific airport. It tells pilots what weather conditions to expect during a set time window, typically covering 24 or 30 hours.
How It Works#
Meteorologists at authorized weather offices produce TAFs using atmospheric models, surface observations, and upper-air data. Each TAF covers a zone within roughly 5 statute miles (8 km) of the airport it serves.
TAFs follow a strict coded format defined by ICAO. The forecast includes:
- Wind: direction in degrees and speed in knots
- Visibility: reported in statute miles (in the US) or meters (internationally)
- Significant weather: phenomena such as rain, fog, or thunderstorms
- Sky condition: cloud layers and their heights above ground in hundreds of feet
Change groups appear inside the TAF whenever the forecast shifts significantly. The codes FM (from), TEMPO (temporary), and BECMG (becoming) signal how and when conditions are expected to change.
TAFs are issued four times per day, at 0000Z, 0600Z, 1200Z, and 1800Z. Pilots check the valid time group at the start of the TAF to confirm the forecast covers their planned flight time.
Example in Aviation#
A pilot plans a morning departure from a regional airport. She pulls the TAF and reads a TEMPO group showing visibility dropping below 1 statute mile in fog between 0800Z and 1000Z. Her departure is scheduled for 0900Z. That single change group tells her to expect instrument conditions at the airport during her planned window. She adjusts her departure time or prepares an alternate airport accordingly.
Why It Matters#
TAFs are a primary preflight planning tool for instrument flight rules (IFR) operations. Regulations such as 14 CFR §91.103 require pilots to review all available weather information before any flight. A TAF gives the clearest picture of expected conditions at the destination, not just current ones.
Even VFR (visual flight rules) pilots benefit from TAFs. A clear sky at departure means little if the destination airport is forecast to go below VFR minimums two hours later. Reading and understanding a TAF is a basic but critical skill for any pilot.
Key Takeaways#
- A TAF forecasts weather for a 5 SM radius around a specific airport.
- Standard TAFs cover a 24- or 30-hour window, issued four times daily.
- Change groups (FM, TEMPO, BECMG) describe how conditions will shift over time.
- TAFs use ICAO-standard coded format, consistent across most of the world.
- Reviewing the TAF before flight is a legal requirement under 14 CFR §91.103.