Decoding your first METAR and the weather shorthand every pilot has to speak

A METAR (Meteorological Aerodrome Report) is a standardized snapshot of current weather conditions at a specific airport, issued once per hour. Every pilot needs to read METARs fluently — they are the ground truth for go/no-go decisions, crosswind calculations, and legal VFR compliance. The format is universal, the order never changes, and once learned, any METAR can be decoded in about thirty seconds.

What Is a METAR and When Is It Issued?

METAR stands for Meteorological Aerodrome Report (also called a Meteorological Terminal Aviation Routine weather report). It captures observed weather at a specific airport at a specific moment in time.

METARs are issued once per hour, typically between 53 and 59 minutes past the hour. If weather changes significantly between scheduled reports, a SPECI (special observation) is issued using the same format, just off-cycle.

The critical distinction: a TAF (Terminal Aerodrome Forecast) tells you what weather is expected. A METAR tells you what weather is actually happening. When standing on the ramp deciding whether to fly, the METAR is your ground truth.

How Do You Read a METAR From Left to Right?

Every METAR follows the same order, every time. Here is a realistic example:

METAR KORD 271951Z 31010KT 10SM FEW035 SCT070 BKN120 OVC250 18/12 A2992 RMK AO2 SLP038

Each element breaks down as follows.

What Does the Station Identifier Mean?

The first element after “METAR” (or “SPECI”) is the station identifier. KORD is Chicago O’Hare. In the United States, airport identifiers begin with K, followed by the three-letter location code. Canadian airports start with C, Mexican airports with M. This tells you exactly where the observation was taken.

How Do You Read the Date and Time Group?

271951Z means the observation was taken on the 27th day of the month at 1951 Zulu (UTC). The first two digits are the day; the last four digits are the time in Zulu (Coordinated Universal Time). Aviation runs on one clock worldwide — never local time.

Write Zulu time on your kneeboard every time you get a weather update. If the METAR says 1951Z and your clock reads 2130Z, that observation is almost two hours old and you need a fresher one.

How Do You Decode Wind Direction and Speed?

31010KT means wind from 310 degrees true at 10 knots. The first three digits are direction (where the wind is coming from), and the next two or three digits are speed in knots.

Gusts appear after a G: 31010G20KT means 310 degrees at 10 knots, gusting to 20.

Key details:

• METAR wind direction references true north. Controller-reported wind (ATIS, tower) references magnetic north. This difference matters for crosswind calculations, especially at airports with significant magnetic variation. In Chicago, variation is only 3–4 degrees. In Alaska, it can exceed 20 degrees.
• 00000KT means calm wind.
• VRB04KT means variable direction at 4 knots (used when direction is variable and speed is 6 knots or less).
• When wind direction varies between two headings at speeds above 6 knots, the variation range appears in the remarks section.

What Does the Visibility Number Tell You?

10SM means 10 statute miles visibility. In the United States, METAR visibility is always in statute miles (SM). A reported value of 10SM means 10 or greater — it could be 50 miles of crystal-clear air, but the report caps at 10.

Lower visibilities appear as specific values: 2 1/2SM, 1 1/4SM, etc.

For basic VFR in Class E airspace below 10,000 feet, you need at least 3 statute miles of flight visibility. The METAR visibility number is your first check on legal and safe VFR flight.

How Do You Read Weather Phenomena Codes?

Weather phenomena appear between visibility and sky condition. Each uses a standard abbreviation:

• RA — rain
• SN — snow
• FG — fog (visibility below 5/8 statute mile)
• BR — mist (visibility 5/8 to 6 statute miles with moisture)
• HZ — haze
• TS — thunderstorm

Intensity qualifiers modify these codes: a minus sign (-) means light, no sign means moderate, and a plus sign (+) means heavy. So -RA is light rain, and +TSRA is a heavy thunderstorm with rain.

Prefix descriptors add further detail: MI (shallow), BC (patches), PR (partial), DR (drifting), BL (blowing). +BLSN is heavy blowing snow — a very different picture from light snow showers.

The distinction between FG and BR matters for go/no-go decisions. Fog means visibility has dropped below 5/8 of a mile. Mist means reduced visibility with moisture but conditions are not yet that severe.

When TS appears anywhere in the weather phenomena, a thunderstorm is occurring at the station. Even if the rest of the METAR looks benign, a thunderstorm at the field means wait.

How Do You Determine the Ceiling From Cloud Layers?

Sky condition is reported in layers, each with a coverage descriptor and a height in hundreds of feet AGL:

• FEW035 — few clouds at 3,500 feet AGL (1–2 eighths sky coverage)
• SCT070 — scattered at 7,000 feet (3–4 eighths)
• BKN120 — broken at 12,000 feet (5–7 eighths)
• OVC250 — overcast at 25,000 feet (8 eighths, full coverage)

The ceiling is defined as the lowest broken or overcast layer. In this example, the ceiling is 12,000 feet (the BKN120 layer). Few and scattered layers are not the ceiling. On a checkride, examiners expect you to identify the ceiling quickly and correctly — pointing to a scattered layer is a problem.

Clear sky reports: CLR from automated stations (no clouds detected below 12,000 feet) or SKC (sky clear) from human observers.

Why Does the Temperature-Dew Point Spread Matter?

18/12 means the temperature is 18°C and the dew point is 12°C. Below-zero values use M for minus: M03/M08 is -3°C temperature, -8°C dew point.

The spread between temperature and dew point is a critical indicator. When the spread closes, moisture condenses — fog forms, clouds form, visibility drops.

A useful rule of thumb: temperature and dew point converge at roughly 2.5°C per 1,000 feet of altitude gain. With a 6°C surface spread, expect cloud bases near 2,400 feet AGL. This is a solid crosscheck against reported cloud bases.

If the surface spread is 2–3 degrees in late afternoon heading toward evening with calm winds, think radiation fog. Radiation fog thrives on clear skies, light winds, and a narrow temperature-dew point spread.

How Do You Use the Altimeter Setting?

A2992 means the altimeter setting is 29.92 inches of mercury. Set this in your altimeter’s Kollsman window so altitude reads correctly.

The rule of thumb: every 0.10 inches of mercury difference equals roughly 100 feet of altimeter error. If you are set on 29.82 but the actual setting is 29.92, your altimeter reads approximately 100 feet too low.

When the altimeter setting is below 29.92, atmospheric pressure is lower than standard, and your airplane is lower than indicated. The memory aid is “high to low, look out below” — flying from high pressure to low pressure without updating the altimeter means your true altitude is lower than displayed. In mountainous terrain, this error can be fatal.

What Information Is in the Remarks Section?

Everything after RMK contains supplemental data:

• AO1 — automated station without precipitation discriminator
• AO2 — automated station with precipitation discriminator (can distinguish rain from snow; most common type)
• SLP followed by three digits — sea level pressure in millibars (SLP038 = 1003.8 mb)
• TSNO — thunderstorm sensor not operating
• RVRNO — runway visual range sensor out
• Maintenance check indicator — one or more sensors may not be operating normally; treat the report with added skepticism and verify with a second source

How Should You Use METARs During Preflight Planning?

Step 1: Check the time. Is this METAR current? If it is more than an hour old with no SPECI available, conditions may have changed.

Step 2: Check ceiling and visibility. Can you legally fly VFR? In Class G and E airspace below 10,000 feet, you need at least 3 statute miles visibility and must remain 500 feet below, 1,000 feet above, and 2,000 feet horizontally from clouds. A ceiling of 800 feet broken means VFR is off the table unless you obtain a Special VFR clearance — and for newer pilots, Special VFR is best avoided.

Step 3: Check the wind. Is it within your personal crosswind limits? A wind of 360 at 18 gusting 25 against runway 270 produces roughly a 90-degree crosswind at 18 gusting 25 knots — too much for most newer pilots.

Step 4: Evaluate the temperature-dew point spread. Is fog likely to develop? Compare the current METAR to the previous hour’s report. Are conditions improving or deteriorating? The trend tells you more than any single observation.

Step 5: Set the altimeter. Check altimeter settings along your route, not just at departure and destination. Pressure can vary significantly across a couple hundred miles.

Step 6: Check METARs along your entire route. If every airport within 50 miles of your destination reports low ceilings while you are VFR, that should weigh heavily on your go/no-go decision — even if the TAF predicts improvement. Forecasts are sometimes wrong. METARs report what is happening right now.

Key Takeaways

• METARs follow a fixed order every time: report type, station, date/time, wind, visibility, weather phenomena, sky condition, temperature/dew point, altimeter, remarks.
• The ceiling is the lowest broken or overcast layer — not few, not scattered.
• METAR winds reference true north; controller winds reference magnetic north — a distinction that matters for crosswind calculations.
• Temperature-dew point spread predicts fog and cloud formation: converging at roughly 2.5°C per 1,000 feet of altitude gain.
• Every flight should begin with reading the current METAR for departure, destination, and airports along the route.