TAF Cheat Sheet: Quick Forecast Reading for Part 107

If METARs are what the weather is right now, TAFs are what it's going to be. TAF stands for Terminal Aerodrome Forecast and the Part 107 exam will expect you to read one. The format borrows a lot from METARs so if you already know those, this is mostly about learning a few new pieces.

The Basic Structure

A TAF looks like this: TAF KBOS 261120Z 2612/2712 28015KT 9999 FEW030 TEMPO 2615/2618 28025G35KT 5SM TSRA BKN020

It starts with TAF, then the station, then when it was issued, then the valid period, and then the forecast broken into time chunks. That valid period is key — a standard TAF covers 24 hours, and some cover 30.

What the Time Groups Mean

The valid period and change groups use the same format: DDHH/DDHH. That's day/hour to day/hour in UTC. So 2612/2712 means from the 26th at 1200Z to the 27th at 1200Z. When the exam gives you a TAF and asks about conditions at a specific time, find which time group covers that window.

The Change Indicators: What Actually Matters

These are the words that tell you conditions are shifting. Know these cold:

• FM (From) — A full change. Everything after FM replaces everything before it. FM2000 means starting at 2000Z, all new conditions apply. This is the most clear-cut one.
• TEMPO (Temporary) — Conditions that will last less than an hour at a time and cover less than half the time period. Think of it as a heads up, not a guarantee. If TEMPO shows something bad, it might happen.
• BECMG (Becoming) — A gradual change that will be complete by the end of the time window. BECMG 2618/2620 means conditions will transition between 1800Z and 2000Z on the 26th.
• PROB30 / PROB40 — Probability. PROB30 means a 30% chance of those conditions, PROB40 means 40%. These show up with TEMPO sometimes. Low probability stuff is worth noting but not panicking over.

What Matters on the Exam vs. What Doesn't

Matters a lot: reading the valid period correctly, understanding FM vs. TEMPO, identifying whether conditions at a given time meet Part 107 minimums (3SM visibility, 500 feet below clouds), and spotting TS anywhere in the forecast.

Matters less: memorizing every possible weather phenomena code or getting deep into probability math. The exam tests whether you can read a TAF and make a go/no-go call, not whether you can recite the entire format from memory.

A Quick Example

TAF KORD 261720Z 2618/2718 21010KT 9999 SCT040 FM270200 18005KT 9999 FEW015 TEMPO 2704/2708 4SM BR OVC008

From the 26th at 1800Z to the 27th at 0200Z: winds from 210 at 10 knots, good visibility, scattered clouds at 4,000 feet. Fine to fly. From 0200Z on the 27th (that FM): winds calm down, few clouds at 1,500 feet, still fine. But between 0400Z and 0800Z there's a TEMPO for 4 miles visibility in mist with an overcast at 800 feet. That TEMPO window is sketchy. Ceiling at 800 feet is below the 1,000 foot mark where it starts to get tight, and 4SM is legal but close. If the exam asks whether conditions are acceptable during that TEMPO window, the answer depends on whether you read it carefully.

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