Decoding the METAR and the thirty seconds of alphabet soup that tell you if the sky is safe

A METAR is a standardized weather observation that gives pilots a complete snapshot of atmospheric conditions at a specific airport at a specific moment in time. In roughly thirty seconds of reading, you get wind, visibility, clouds, temperature, and pressure — everything needed for a go or no-go decision. Once you learn the format, you never unlearn it, and your checkride examiner will ask you to decode one.

This guide walks through every group in a real METAR — not a textbook example with perfect weather, but a messy one that forces actual decision-making.

What does each part of a METAR mean?

Here’s a real-world METAR for Chicago Midway:

KMDW 261853Z 24015G25KT 6SM HZ FEW045 BKN080 OVC120 18/15 A2992 RMK AO2

Every METAR follows the same structure. Here’s each group decoded:

KMDW — The station identifier. The K prefix indicates a station in the contiguous United States. MDW is Chicago Midway’s three-letter code. Every METAR starts with who’s reporting.

261853Z — The date and time of the observation. 26 is the day of the month. 1853Z is the time in Zulu (Coordinated Universal Time). This observation was taken on the 26th at 1853Z, which converts to 1:53 PM Central Daylight Time.

METARs are routinely issued at 53 minutes past the hour, not on the hour. This gives the automated system or human observer time to compile data for publication near the top of the hour. If conditions change significantly between routine observations, a SPECI (special) METAR is issued — when you see one, pay extra attention.

How do you read wind in a METAR?

24015G25KT breaks down as:

• 240 — Wind direction in degrees true north. This wind comes from 240 degrees, roughly southwest.
• 15 — Sustained speed in knots.
• G25 — Gusting to 25 knots.

A 10-knot gust spread (15 to 25) is significant. If your personal wind limit is 15 knots, the sustained wind is already at your boundary and the gusts blow past it.

Think about runway alignment. If Midway is landing runway 31L, a 240-degree wind creates roughly a 50-degree crosswind. At 15 gusting 25, the crosswind component could be 12 to 15 knots or more. The METAR gives you the raw data — the decision is yours.

Two additional wind codes to know:

• VRB — Variable wind direction, typically seen with winds under 6 knots.
• 240V290 — Wind direction varying between 240 and 290 degrees.

What does visibility tell you in practice?

6SM HZ — Prevailing visibility is 6 statute miles (not nautical miles) with haze (HZ).

Six miles exceeds the 3 statute miles required for VFR in controlled airspace. But 6 miles in haze does not feel like 6 miles in the cockpit. Haze washes out the horizon, makes traffic difficult to spot, and with a low sun angle, effective visibility drops well below the official number. Everything turns milky and indistinct.

The real skill isn’t reading the number — it’s understanding what that number means from the pilot’s seat.

How do you decode weather phenomena codes?

Common codes you’ll encounter:

Intensity prefixes modify these codes: minus (-) means light, no prefix means moderate, plus (+) means heavy. So +TSRA is a heavy thunderstorm with rain. -SHRA is light rain showers.

A common checkride question: what’s the difference between BR (mist) and FG (fog)? It’s visibility. Water droplets reducing visibility to between 5/8 mile and 6 miles are reported as mist. Below 5/8 mile, it becomes fog. Same phenomenon, different intensity. If you see FG in a METAR, that airport is at or near instrument conditions.

How do you determine the ceiling from cloud layers?

FEW045 BKN080 OVC120 reports three cloud layers in ascending order. Heights are in hundreds of feet above ground level (AGL), not MSL.

• FEW045 — Few clouds (1–2 oktas) at 4,500 feet AGL
• BKN080 — Broken layer (5–7 oktas) at 8,000 feet AGL
• OVC120 — Overcast (8 oktas) at 12,000 feet AGL

The ceiling is defined as the lowest broken or overcast layer. Here, the ceiling is 8,000 feet (the broken layer). The few layer at 4,500 feet is not the ceiling — few clouds don’t cover enough sky. Misidentifying the ceiling is a common checkride mistake.

VFR in controlled airspace requires at least a 1,000-foot ceiling. An 8,000-foot ceiling is comfortable. But if that broken layer were at 1,200 feet, you’d be at minimums. Overcast at 800 feet means IFR conditions.

Watch for VV (vertical visibility). VV008 means vertical visibility of 800 feet with no defined cloud base, typically caused by fog or heavy precipitation. This is an indefinite ceiling and counts as a ceiling for determining flight rules.

Why does the temperature-dewpoint spread matter?

18/15 — Temperature 18°C, dewpoint 15°C. Both reported in Celsius.

The 3-degree spread is tight. When temperature and dewpoint are within 2–3 degrees, the probability of fog formation is high, especially with dropping temperatures. As evening approaches, that spread closes. When temperature equals dewpoint, condensation occurs — fog, mist, reduced visibility.

This METAR shows 6 miles visibility right now, but that narrow spread is a warning. If your flight returns to Midway in three hours, conditions could be significantly worse. The METAR is a snapshot of the present, but the temp-dew spread hints at the future.

How do you use the altimeter setting?

A2992 — Barometric pressure of 29.92 inches of mercury. The four-digit number has an implied decimal after the second digit. Set this in your altimeter’s Kollsman window for accurate altitude readings in that area.

An incorrect altimeter setting means your indicated altitude is wrong. The memory aid: “High to low, look out below.” Flying from high pressure to low pressure without resetting your altimeter places your actual altitude lower than indicated — dangerous near terrain, especially in instrument conditions.

What’s in the remarks section?

RMK AO2 — The remarks section. AO2 indicates an automated station with a precipitation discriminator (it can distinguish rain from snow). AO1 stations cannot.

Remarks can contain pressure tendency, temperature and dewpoint to the tenth of a degree, peak wind, sea level pressure, lightning data, and more. One critical remark to know: a dollar sign ($) at the end means the station needs maintenance and the data may be unreliable. Cross-reference with another source before making decisions based on that report.

How should you use METARs in preflight planning?

Don’t read just your destination’s METAR. Check the METAR for your departure airport, destination, alternate, and airports along your route. Weather doesn’t stop at airport boundaries. If every station within 50 miles reports 3 miles in mist and overcast at 1,000, your unmonitored grass strip won’t have clear skies.

Compare the METAR to the TAF. The METAR shows current conditions; the TAF shows the forecast. If the METAR is better than predicted, ask why — temporary improvement? Delayed front? If the METAR shows worse conditions than forecast, that’s a red flag. The atmosphere is outrunning the model.

Look at trends. Pull the last several METARs for your destination. Is visibility improving or dropping? Is the ceiling lifting or lowering? A single METAR is a photograph. A sequence of METARs is a movie — and movies reveal where the story is heading.

What will the examiner ask about METARs?

On your checkride, expect three questions when handed a METAR:

1. What are the current conditions? (Knowledge question)
2. What are the flight rules — VFR, MVFR, IFR, or LIFR? (Knowledge question)
3. Would you go or not go? (Judgment question — this is the one that matters)

The METAR is ground truth. Forecasts are educated guesses. Models are math. But the METAR is what was actually observed at that airport at that time. Learn to read it fluently, read it quickly, and let it change your mind when it tells you something you don’t want to hear.

Key Takeaways

• Every METAR follows the same structure: station, date/time, wind, visibility, weather, clouds, temp/dewpoint, altimeter, remarks — learn the order once and you can decode any METAR
• The ceiling is the lowest broken or overcast layer, not just the lowest cloud layer reported — misidentifying this is a common checkride error
• A tight temperature-dewpoint spread (2–3°C) warns of potential fog formation even when current visibility looks acceptable
• Never rely on a single METAR — compare with TAFs, check stations along your route, and review sequential observations to spot trends
• Reported visibility doesn’t equal perceived visibility — haze, sun angle, and other factors can make official numbers feel optimistic from the cockpit

References: FAA Advisory Circular AC 00-45H (Aviation Weather Services), Pilot’s Handbook of Aeronautical Knowledge Chapter 13.