How to read a TAF

A METAR tells you what the weather is. A TAF tells you what a forecaster thinks it will be, in a five-mile circle around the airport, for the next 24 or 30 hours.

Last updated August 2026

TAFs are issued four times a day — roughly 00, 06, 12 and 18 UTC — and amended whenever the forecast goes materially wrong. They use the same abbreviations as a METAR, so if you can read one you already know most of this. What is genuinely different is the change groups, and that is where most misreadings happen.

A complete example

TAF KSEA 081120Z 0812/0918 19005KT P6SM SCT230
     FM081300 22005KT P6SM SCT009
     FM081700 23005KT P6SM SCT200
     TEMPO 0820/0823 4SM -RA BKN015

Line by line: issued on the 8th at 11:20 UTC, valid from the 8th at 12:00 UTC until the 9th at 18:00 UTC. Initially wind 190° at 5, visibility more than 6 statute miles, scattered at 23,000. From 13:00 the wind backs slightly and a scattered layer drops to 900 feet. From 17:00 that layer lifts back to 20,000. And temporarily between 20:00 and 23:00, visibility drops to 4 miles in light rain with a broken layer at 1,500.

The header

081120Z 0812/0918 — issue time, then the validity period as day/hour pairs. 0812 is the 8th at 12:00 UTC; 0918 is the 9th at 18:00 UTC. A TAF AMD prefix means amended, TAF COR corrected. If you see NIL, no forecast is available.

P6SM means "plus 6 statute miles" — visibility greater than 6. It is the TAF equivalent of a METAR's 10SM ceiling on the scale.

Change groups — the part that matters

FM — from

FM081300 means a rapid, permanent change beginning at 13:00 UTC on the 8th. Everything that follows completely replaces the previous conditions, and stays in force until the next FM or the end of the TAF. If you remember one thing: FM wipes the slate. Anything not restated is no longer forecast.

BECMG — becoming

BECMG 0814/0816 describes a gradual transition expected to happen at some point within that window, usually over an hour or two. After the window, the new conditions apply. Only the elements mentioned change; everything else carries forward.

TEMPO — temporary

TEMPO 0820/0823 means fluctuations expected to occur for less than an hour at a time, and in total less than half the period. The conditions before the TEMPO remain the prevailing forecast — the TEMPO is what might briefly interrupt it.

TEMPO is not a maybe you can ignore. For planning purposes, treat a TEMPO group as a condition you should expect to encounter at some point in that window. If the TEMPO puts the field below your personal minimums, you need an alternate, even though the prevailing line looks comfortable.

PROB30 and PROB40

A 30% or 40% probability of the conditions that follow. You will not see PROB50 or higher — above that a forecaster is expected to commit. PROB groups often wrap a TEMPO, as in PROB30 TEMPO 0902/0906 2SM TSRA.

Working out the weather at your ETA

This is the practical skill. Do it in order:

Convert your ETA to UTC and note the day.
Find the last FM group at or before that time. That is your baseline — everything in it applies.
Check for a BECMG window that has already completed before your ETA. If so, apply those changes on top.
Check whether any TEMPO or PROB window overlaps your ETA. If it does, plan for it.

In the example above, an arrival at 21:30 UTC on the 8th sits after FM081700 — so the prevailing forecast is wind 230/5, more than 6 miles, scattered at 20,000 — but it falls inside TEMPO 0820/0823, so you should also be ready for 4 miles in rain with a 1,500-foot ceiling.

What a TAF will not tell you

It only covers a five-statute-mile radius of the airport. The weather along your route is not in here; that is what area forecasts, AIRMETs and SIGMETs are for.
Not every airport has one. TAFs are issued for a limited set of fields. Smaller airports have METARs only, or nothing.
Seasonal service. Some fields only get TAF service part of the year — Wittman Regional at Oshkosh, for example, is forecast during AirVenture and largely not otherwise. An old TAF at such a field can look valid at a glance.
It is a forecast. Compare it against the current METAR. If the observation has already diverged badly from the forecast, trust the observation and expect an amendment.

Reading it in Flight Kneeboard

Open any airport, choose Weather → TAF. The raw text is shown with each group tappable — tap FM092000 or SCT009 and the decode appears in place. Below it, the TAF Breakdown renders the whole forecast as a timeline you can switch between flight category, sky coverage, visibility and wind, so you can see at a glance when the field goes down and when it comes back. That is usually faster than parsing the change groups by hand, though it is worth being able to do both.

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