What are common Part 107 exam mistakes on decoding metars?

Calling a scattered layer a ceiling. The fix: Ceilings are BKN, OVC, or VV only. SCT and FEW do not cap you — but you still owe any cloud 500/2,000 clearance. Reading cloud heights as MSL. The fix: METAR cloud bases are AGL at the reporting station — convenient for AGL-thinking drone pilots. Missing the Z. The fix: All METAR times are UTC. An 1853Z observation is not 6:53 p.m. local except in one time zone.

How long does this lesson take?

About 13 minutes to read, plus a ten-question check in the free course.

Decoding METARs

~13 min read · Decode a METAR element by element: wind, visibility, weather, clouds, temp/dewpoint.

A METAR is the weather that IS — an hourly coded surface observation. The exam gives you a raw string and asks for wind, visibility, ceiling, or temperature-dewpoint spread. Decoding is a mechanical skill: learn the field order once and the questions become free points.

The field order

A METAR reads left to right in fixed order: station, date/time, wind, visibility, weather phenomena, clouds, temperature/dewpoint, altimeter, remarks. Example: `METAR KTUL 121853Z 22012G20KT 6SM -RA BKN008 OVC015 18/16 A2992 RMK AO2`. Station KTUL; day 12 of the month at 1853 Zulu (UTC); wind from 220° true at 12 knots gusting 20; visibility 6 statute miles; light rain; broken clouds at 800 ft AGL, overcast 1,500; temperature 18°C, dewpoint 16°C; altimeter 29.92 inHg.

Time is always Zulu — convert to local for your ops window
Wind: direction FROM, in degrees true, speed/gusts in knots
Cloud heights are in hundreds of feet AGL

Weather and sky codes

Intensity prefixes: minus (-) light, none moderate, plus (+) heavy. Common codes: RA rain, SN snow, TS thunderstorm, BR mist (visibility 5/8 to 6 SM), FG fog (below 5/8 SM), HZ haze, DZ drizzle, SH showers, FZ freezing. Sky cover by eighths (oktas): SKC/CLR clear, FEW 1–2, SCT 3–4, BKN 5–7, OVC 8. A ceiling is the lowest BROKEN or OVERCAST layer — scattered layers are not ceilings. VV (vertical visibility) reports an indefinite ceiling, e.g. VV004 in fog.

-/+ modify intensity; TSRA = thunderstorm with rain
Ceiling = lowest BKN or OVC (or VV) layer
SPECI = an unscheduled special observation for rapidly changing weather

Reading it as a drone pilot

Match the fields to Part 107 minimums: visibility must be at least 3 SM, and your 400-ft operation needs 500 ft of clearance below any cloud — so a ceiling below roughly 900 ft AGL pins you down proportionally. Gust spreads matter for small airframes: 12G20 means 8 knots of shear-like variability on approach to a hover. Temperature/dewpoint spread warns of fog when it closes within about 2°C.

Worked example

METAR KDAL 141753Z 18010G18KT 4SM HZ SCT009 BKN012 30/24 A3002. Can you legally and practically fly a 400-ft AGL inspection at 1 p.m. local (1800Z)?

Visibility 4 SM ≥ 3 SM: legal. Ceiling: SCT009 is not a ceiling; BKN012 is — 1,200 ft AGL. Cloud clearance requires 500 ft below: 1,200 − 500 = 700 ft AGL is your practical cloud-driven cap, so a 400-ft mission fits with margin. Wind 10 gusting 18 knots from 180°: legal (no wind limit in Part 107) but check your airframe's gust tolerance. Temp/dewpoint 30/24: a 6°C spread, no imminent fog. Verdict: legal and flyable at 400 ft; the binding number was the BKN012 layer, not visibility.

Common exam pitfalls

Calling a scattered layer a ceiling.

Ceilings are BKN, OVC, or VV only. SCT and FEW do not cap you — but you still owe any cloud 500/2,000 clearance.

Reading cloud heights as MSL.

METAR cloud bases are AGL at the reporting station — convenient for AGL-thinking drone pilots.

Missing the Z.

All METAR times are UTC. An 1853Z observation is not 6:53 p.m. local except in one time zone.

SWVW-CTA: Station, When, Wind, Visibility — Clouds, Temp, Altimeter.

Recap

Field order: station, time(Z), wind, visibility, weather, clouds, temp/dew, altimeter
Wind: from-direction in degrees true, knots, G for gusts
Sky cover in oktas: FEW/SCT/BKN/OVC; ceiling = lowest BKN/OVC/VV
Cloud bases in hundreds of feet AGL
-/+ prefixes set intensity; BR vs FG is a visibility split at 5/8 SM
Check 3 SM visibility and 500-below cloud clearance against the report