METAR&TAFObservation & Forecast · Decoder
Reference · ForecastICAO Annex 3 · NWS

TAF explained

How to read the Terminal Aerodrome Forecast — issued every 6 hours, valid for the next 24–30.

A TAF is a forecast covering the airspace within a 5-statute-mile radius of an airport for the next 24 to 30 hours. TAFs are issued every 6 hours by the National Weather Service (00Z, 06Z, 12Z, 18Z) and amended when conditions change significantly. The format reuses METAR field conventions for wind, visibility, weather, and sky, so if you can read a METAR you're most of the way to reading a TAF.

A typical TAF looks like this:

TAF KLAX 081720Z 0818/0924 27012KT P6SM SCT025
   FM090300 28010KT P6SM BKN015
   TEMPO 0903/0907 4SM BR BKN008
   BECMG 0915/0918 27015KT P6SM SCT040

Header

  • TAFReport type. TAF AMD = amended, TAF COR = corrected.
  • KLAXICAO station identifier.
  • 081720ZIssue day and UTC time. Here: 8th, 17:20 UTC.
  • 0818/0924Valid period: from day 8 18:00Z through day 9 24:00Z.

Initial period

The first set of fields after the valid period applies to the start of the forecast and continues until a change indicator overrides it. Fields use METAR syntax: wind, visibility, weather, sky condition.

Change indicators

FM

Rapid change

A complete change at the stated time. Conditions before are the previous group's; after are the new group's. FM090300 = from day 9 03:00Z.

BECMG

Gradual change

Change occurs gradually between the two times. The transition completes by the second time and the new conditions persist after. BECMG 0915/0918 = becoming, between day 9 15Z and 18Z.

TEMPO

Temporary fluctuations

Temporary fluctuations expected for less than half the indicated period. The base forecast continues; TEMPO conditions occur intermittently within it.

PROB30/40

Probabilistic

30% or 40% probability of the stated conditions in the indicated period. Used when forecaster confidence is below typical.

Notes

  • TAFs are produced for ~700 airports in the US. Smaller fields rely on the nearest TAF.
  • A WS group encodes low-level wind shear: WS020/27050KT = wind shear at 2,000 ft AGL, from 270° at 50 kt.
  • The NSW token in a change group means "no significant weather" expected during that period.

Source Authoritative source: aviationweather.gov. This page is informational only — verify forecasts with the official briefing for any flight-related decision.