How to Read a METAR: The Complete Pilot's Guide

WHAT IS A METAR, AND HOW CURRENT IS IT?

A standard METAR is valid for one hour from its observation time. FAA regulations under 14 CFR Part 91.103 require pilots to familiarize themselves with all available weather information before any flight. A METAR becomes stale after 60 minutes. For rapidly changing conditions, that one-hour window matters significantly.

METAR vs. SPECI is a distinction every pilot must understand: • METAR — Scheduled hourly report • SPECI — Special observation issued between scheduled reports when conditions change rapidly or cross significant thresholds (visibility drops below 3 SM, ceiling drops below 1,000 ft, a tornado or funnel cloud is observed, or wind shifts occur)

When a SPECI appears in a briefing, treat it as the most current observation. It supersedes the previous hourly METAR for operational planning purposes.

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WHERE TO FIND METARS

• aviationweather.gov — The FAA and NOAA official source. Free, reliable, no account required. Provides raw and decoded METARs. • ForeFlight — Displays METARs on the map with color-coded flight categories. Supports raw and decoded views. • Garmin Pilot — Similar capability to ForeFlight with SiriusXM weather integration. • 1800wxbrief.com — Leidos standard briefing portal. METARs are integrated into official weather briefings. • Aviation Hub METAR Decoder — Paste any raw METAR for an instant plain-language decode.

Always retrieve METARs as close to departure as operationally practical. A METAR that is 45 minutes old during preflight may be significantly different from conditions at wheels-up.

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FULL METAR STRUCTURE: REFERENCE EXAMPLE

METAR KLAX 151853Z 27012KT 10SM FEW030 SCT150 24/13 A2992 RMK AO2

| Field | Value | Meaning | |-------|-------|---------| | Report Type | METAR | Scheduled observation | | Station | KLAX | Los Angeles International (ICAO) | | Time | 151853Z | 15th day of month, 1853 UTC | | Wind | 27012KT | From 270° at 12 knots | | Visibility | 10SM | 10 statute miles | | Clouds | FEW030 SCT150 | Few at 3,000 ft, Scattered at 15,000 ft AGL | | Temp/Dew Point | 24/13 | 24°C temperature, 13°C dew point | | Altimeter | A2992 | 29.92 inHg | | Remarks | RMK AO2 | Automated station with precipitation sensor |

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DECODING WIND: GUSTS, VARIABLES, AND CALM

The wind group follows a consistent format: dddffKT, where ddd is the three-digit direction in degrees true and ff is speed in knots.

Gust conditions add a G and peak gust speed: • 28018G32KT — Wind from 280° at 18 knots, gusting to 32 knots • Gusts exceeding the mean speed by 10 knots or more are always reported

Variable wind direction uses the designator VRB when direction is shifting and speed is 6 knots or less: • VRB04KT — Variable direction, 4 knots

When winds are stronger but direction varies significantly, a variable sector is appended: • 27015KT 230V310 — Wind averaging 270° at 15 knots, varying between 230° and 310°

Calm wind is reported as 00000KT. This is relevant for runway selection and crosswind calculations.

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VISIBILITY: FRACTIONS, MINIMUMS, AND RVR

Visibility in U.S. METARs is reported in statute miles. Fractional values appear when visibility is below 1 SM: • 1/4SM — One-quarter statute mile visibility • 1 1/2SM — One and one-half statute miles • M1/4SM — Less than one-quarter statute mile (M means "less than")

Runway Visual Range (RVR) is reported when visibility falls below 1 SM. It measures the horizontal distance a pilot can see down the runway centerline using high-intensity runway lights as the reference. RVR appears as:

R28L/2400FT — Runway 28 Left, RVR 2,400 feet

RVR suffixes indicate trend: • U — Upward (improving) • D — Downward (decreasing) • N — No change

RVR values below 1,800 feet indicate conditions at or near CAT II/III ILS minimums. Pilots operating under IFR must know their aircraft and approach category minimums in relation to reported RVR.

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WEATHER PHENOMENA CODES

Present weather is one of the most information-dense fields in a METAR. Intensity qualifiers precede the phenomenon code: • - (minus) — Light • No prefix — Moderate • + (plus) — Heavy • VC — In the vicinity (5–10 SM from the airport)

Precipitation codes: • RA — Rain • SN — Snow • GR — Hail (diameter 1/4 inch or greater) • GS — Small hail or snow pellets • DZ — Drizzle • PL — Ice pellets • SG — Snow grains • FZRA — Freezing rain (significant icing hazard) • FZDZ — Freezing drizzle

Obscuration and other phenomena: • FG — Fog (visibility below 5/8 SM) • BR — Mist (visibility 5/8 SM to 6 SM) • HZ — Haze • FU — Smoke • DU — Dust • SA — Sand • BLSN — Blowing snow

Thunderstorm codes: • TS — Thunderstorm (no precipitation at station) • TSRA — Thunderstorm with rain • +TSRA — Heavy thunderstorm with rain • VCTS — Thunderstorm in the vicinity

A report showing +TSRA is a serious red flag. It indicates heavy rain embedded in a thunderstorm directly over or adjacent to the field.

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CLOUD COVERAGE TERMS

Cloud layers are reported from lowest to highest. Heights are AGL (above ground level), reported in hundreds of feet. • SKC — Sky clear (used by human observers) • CLR — Clear below 12,000 ft (used by automated stations) • FEW — 1 to 2 oktas (1/8 to 2/8 sky coverage) • SCT — Scattered, 3 to 4 oktas • BKN — Broken, 5 to 7 oktas (counts as a ceiling) • OVC — Overcast, 8 oktas (counts as a ceiling) • VV — Vertical visibility (used when sky is obscured, e.g., VV004 means vertical visibility 400 ft)

A ceiling is defined as the lowest broken or overcast layer, or the vertical visibility when the sky is obscured. This distinction directly determines IFR versus VFR conditions.

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FLIGHT CATEGORIES

Flight categories are determined by ceiling and visibility. The more restrictive value sets the category.

| Category |