3.4 Reading METAR Reports

Decoding the METAR

A METAR (Meteorological Aerodrome Report) is the standardized current-conditions observation for an airport. The FAA test supplement (FAA-CT-8080-2H figures) gives you raw METARs and asks you to extract a fact or judge legality. Decode fields in fixed order, left to right.

METAR KORD 121755Z 27009KT 1SM BR OVC003 02/01 A2980 RMK AO2

Field-by-Field

That KORD report is below Part 107 minimums: 1 SM visibility is under 3 SM, and the 300 ft overcast ceiling makes 500 ft of cloud clearance impossible.

Wind Group: dddssKT or dddssGggKT

• ddd = direction the wind is blowing from, in degrees referenced to true north, rounded to the nearest 10
• ss = sustained speed in knots
• G + gg = gust to that speed

True vs. magnetic — a guaranteed exam trap. A written/printed METAR (and winds-aloft FB forecasts) give direction in true north. The same winds spoken to you over the radio — ATIS, AWOS/ASOS broadcasts, and tower instructions — are referenced to magnetic north, because runway numbers are magnetic. The memory rule is "if you read it, it's true; if you hear it, it's magnetic." Because the FAA test hands you a printed METAR figure, the wind in any UAG question is true north.

Visibility

Reported in statute miles, fractions allowed: 10SM, 3SM (the Part 107 floor), 1 1/2SM, 1/2SM, 1/4SM. Anything under 3SM is a no-go for visibility.

Weather Phenomena

Intensity: - light, none = moderate, + heavy, VC = in the vicinity (5-10 SM). Example: +TSRA = heavy thunderstorm with rain.

Sky Condition: CCChhh

• CCC = FEW, SCT, BKN, or OVC
• hhh = height in hundreds of feet AGL (multiply by 100)

Temperature / Dew Point and Altimeter

• Temp/dew point in Celsius, slash-separated; M = minus. M03/M05 = −3 deg C / −5 deg C.
• Altimeter = A plus four digits, in inches Hg. A2992 = 29.92 (standard); A3010 = 30.10 (high pressure).

Full Worked METAR

METAR KJFK 151853Z 32015G28KT 10SM FEW050 SCT250 24/09 A3001 RMK AO2

• Station/time: JFK, 15th, 1853 UTC
• Wind: from 320 deg at 15 kt, gusting 28 kt
• Visibility: 10 SM (well above 3 SM)
• Sky: few at 5,000 ft, scattered at 25,000 ft — no ceiling
• Temp/dew point: 24/9 deg C (15 deg spread, dry, no fog risk)
• Altimeter: 30.01 inches Hg

Legality: visibility passes, and the lowest layer (5,000 ft) leaves far more than 500 ft of clearance above a 400 ft flight ceiling — a go from a weather-minimums standpoint, though the Remote PIC must still judge the 28 kt gusts against the aircraft.

A Second Worked METAR

METAR KDEN 091152Z 09004KT 1/2SM FG VV002 M02/M03 A3015 RMK AO2

• Station/time: Denver, 9th, 1152 UTC
• Wind: from 090 deg at 4 kt — nearly calm
• Visibility: 1/2 SM — below the 3 SM minimum
• Weather: FG (fog)
• Sky: VV002 = indefinite ceiling, vertical visibility 200 ft (VV appears when the sky is obscured)
• Temp/dew point: −2 / −3 deg C (1 deg spread, saturated)
• Altimeter: 30.15 inches Hg

This is a clear no-go: half-mile visibility in fog with a 200 ft obscured ceiling. Notice how the nearly calm wind, freezing temperatures, and 1 deg dew point spread together describe classic radiation fog from Section 3.3 — the coded report and the theory reinforce each other.

Decoding Strategy for the Exam

Work left to right and answer only what is asked. If the question wants the ceiling, find the lowest BKN/OVC (or VV) group and convert hundreds of feet. If it wants legality, check visibility against 3 SM first, then cloud clearance, then note that no numeric wind limit exists. Do not over-decode — many candidates lose time translating remarks (the RMK group) that the question never references.

Common METAR Traps

• Misreading the day vs. time. 121755Z is the 12th day at 1755 UTC, not 12:17.
• Dropping the M (minus). M06 is −6 deg C; ignoring it flips the sign and the icing risk.
• Confusing true and magnetic wind. A printed METAR reports wind from true north; only winds spoken over ATIS/AWOS/tower are magnetic. "If you read it, it's true."
• Counting FEW/SCT as a ceiling when judging cloud clearance and legality. Only BKN, OVC, or a VV (vertical visibility) group establishes a ceiling.
• Reading altimeter as a pressure altitude. A2992 is just the local altimeter setting (29.92 in Hg); it is not the field elevation or a density-altitude figure.