The METAR - Reading the Ground Truth Behind Every Go/No-Go Decision

A METAR (Meteorological Aerodrome Report) is the only true snapshot of current conditions at a specific airport, measured and reported within the last hour. Every other product in your weather briefing - TAFs, area forecasts, prog charts, winds aloft - is a prediction. The METAR is ground truth, and reading it clearly may be the most critical skill you build as a student pilot.

What Is a METAR and How Is It Different from a Forecast?

Every weather product you’ll use in flight planning except the METAR is some form of educated guess about what the atmosphere will do. The Terminal Aerodrome Forecast (TAF), area forecast discussions, prog charts, and winds aloft products are all predictions.

The METAR tells you what is happening right now, at a single location. When you’re deciding whether to fly, that distinction matters enormously.

METARs are issued every hour, typically around 50–55 minutes past the hour. You’ll also encounter SPECI (special observation) reports, which are issued any time conditions change significantly between scheduled observations. If a report is labeled SPECI, something shifted fast enough that it couldn’t wait.

How Do I Read a METAR? A Complete Example

Here’s a realistic observation to decode element by element:

KORD 291553Z 27015G24KT 3SM -RA BR BKN012 OVC025 14/12 A2989

Each block represents a specific piece of information. None of it is arbitrary.

What Does the Station Identifier Tell Me?

KORD is Chicago O’Hare International Airport. In the United States, most airports use a four-letter identifier beginning with K. Some smaller fields use two- or three-letter identifiers without the K prefix - holdovers from an older system.

Always verify you’re pulling the METAR for the correct airport. Grabbing the wrong station’s report by mistake happens more than pilots admit.

How Do I Read the Date and Time in a METAR?

291553Z breaks down as: 29 (the 29th of the month), 1553 (the time), and Z (Zulu, or Coordinated Universal Time).

All aviation weather is reported in Zulu. Not local time. Not adjusted for daylight saving. This is a foundational habit to build immediately. Central Daylight Time is Zulu minus 5, so 1553Z is 10:53 a.m. in Chicago.

How Do I Read Wind Information in a METAR?

27015G24KT contains three pieces of data:

• 270 - wind direction in degrees magnetic (due west). Wind direction is always where the wind is coming from, not where it’s going.
• 15 - sustained wind speed in knots
• G24 - gusting to 24 knots

Runway numbers are based on magnetic heading. Runway 27 points roughly west, so this is nearly a direct headwind - favorable for operations. A wind from 360° on the same runway would produce a crosswind you’d need to calculate before starting the engine.

If you see VRB in place of a direction, the wind is variable with no consistent heading. This typically accompanies very light winds of 3 knots or less.

What Does Visibility in a METAR Mean for VFR Flight?

3SM means three statute miles. The United States reports visibility in statute miles; most of the rest of the world uses meters - a detail that catches pilots off guard the first time they fly internationally.

Three statute miles is the legal floor for VFR operations in Class E airspace. If visibility is reported as P6SM, the P means “plus” - visibility exceeds six statute miles, which is the maximum the report captures. Below a quarter mile, you’ll see M1/4SM, where M means “less than.”

Three miles is technically legal. Whether it’s operationally appropriate depends heavily on the ceiling, terrain, and trend - all of which you still need to evaluate.

How Do I Decode Present Weather Codes?

-RA BR contains two codes. RA is rain; the minus sign indicates light intensity. A plus sign means heavy; no symbol means moderate. BR is mist - water droplets reducing visibility to between 5/8 and 6 statute miles.

Key weather codes worth knowing cold:

• DZ - drizzle
• SN - snow
• FG - fog. Fog means visibility has dropped below 5/8 of a statute mile. An airport reporting FG is below basic VFR minimums, full stop.
• TS - thunderstorm. If TS appears anywhere near your route, it’s a conversation stopper until you know exactly where those cells are and where they’re heading.
• FZRA - freezing rain. An icing hazard that can coat an airframe faster than you can react.
• VC - in the vicinity, typically 5 to 10 miles from the airport. VCSH means showers are nearby even if the field itself is clear.

How Do I Determine My Ceiling from a METAR?

BKN012 OVC025 means a broken layer at 1,200 feet and overcast at 2,500 feet. Both altitudes are above ground level (AGL), not mean sea level.

Cloud coverage codes:

• FEW - 1/8 to 2/8 of the sky covered
• SCT (scattered) - 3/8 to 4/8
• BKN (broken) - 5/8 to 7/8
• OVC (overcast) - 8/8, complete coverage

Your ceiling is the lowest broken or overcast layer. Scattered layers don’t count. In this example, the ceiling is 1,200 feet AGL - the broken layer. The overcast above it doesn’t change the calculation.

A 1,200-foot ceiling over flat terrain in Illinois is a meaningfully different situation than 1,200 feet over the western Appalachians or the Colorado foothills. Legal minimums and safe minimums are not always the same thing. Know your terrain and obstacles.

What Does the Temperature/Dewpoint Spread Tell Me?

14/12 means temperature 14°C, dewpoint 12°C - a spread of just two degrees.

This number is consistently underweighted by student pilots. When temperature and dewpoint converge, the atmosphere approaches saturation. That’s where fog forms, low stratus develops, and visibility collapses. A two-degree spread with active precipitation is a narrow margin.

If the rain cools the surface air by another two degrees, the spread closes to zero and the airport could go IMC in the time it takes you to fly there from 30 miles out.

A single METAR is one frame of a movie. Pull up several consecutive METARs in sequence and watch the trend. Is the ceiling rising or falling? Is the dewpoint spread widening or closing? The atmosphere tells you what it’s doing if you give it more than one data point.

How Do I Use the Altimeter Setting?

A2989 means 29.89 inches of mercury. Dial this into the Kollsman window of your altimeter before every flight, and update it every time you receive a new ATIS or hear a current altimeter setting from ATC.

Your altimeter doesn’t measure altitude directly - it measures air pressure and converts that to altitude based on the setting you provide. Flying from high pressure into lower pressure without updating means your altimeter reads higher than your actual altitude. The old memory aid holds: “High to low, look out below.” Updating takes two seconds. There’s no excuse to skip it.

What’s in the METAR Remarks Section?

The remarks section follows the main body and contains information that didn’t fit the standard format. Two designations you’ll see regularly:

• AO1 - automated station without a precipitation sensor that can distinguish liquid from frozen precipitation
• AO2 - automated station with that sensor. At an AO1 station in winter, you may not know from the report alone whether that precipitation is rain or snow.

Other common remarks:

• SLP followed by digits - sea level pressure
• T group - temperature and dewpoint to the nearest tenth of a degree, more precise than the main body
• PKWND - peak wind, the highest gust recorded during the past hour

Don’t skip the remarks. They frequently contain operationally significant data.

How Do I Use a METAR to Make a Go/No-Go Decision?

Return to the full KORD observation: light rain and mist, 3 miles visibility, broken ceiling at 1,200 feet, overcast at 2,500, temperature 14°C/dewpoint 12°C, wind 15 gusting 24 knots, altimeter 29.89.

For a VFR private pilot, these conditions sit at the legal floor for Class E airspace. Ceiling is above 1,000 feet, visibility is at 3 miles. Departure would be technically legal.

But consider what you’re departing into: a ceiling that could drop, visibility at the minimum, a closing dewpoint spread, active precipitation, and gusts adding workload on every transition. The Airman Certification Standards (ACS) require applicants to demonstrate sound aeronautical decision-making - not just knowledge of what the regulations permit, but judgment about when the situation demands more than the minimum.

Establish personal minimums and write them down. A reasonable starting point for new private pilots: ceiling no lower than 2,000 feet, visibility no less than 5 miles. That margin lets you manage an unexpected drop, divert without panic, and think instead of react. Those numbers evolve as experience and training deepen, but early in VFR flying, give yourself room.

The METAR is not a checklist. It’s information about what the atmosphere is doing right now, at one location, at one moment in time. Your job is to combine that data with the trend, the forecast, your terrain awareness, and an honest assessment of your own skills - and make a decision you’d be comfortable defending out loud.

Practice reading METARs for airports you know until the string of codes resolves into a picture: gray skies, wet pavement, low visibility, marginal margins. The FAA Aviation Weather Handbook, available as a free download at FAA.gov, covers all of this in depth and is worth keeping within reach.

Key Takeaways

• The METAR is ground truth - every other weather product is a forecast or prediction
• Ceiling is the lowest broken or overcast layer, reported in feet AGL, not MSL
• A temperature/dewpoint spread of 2°C or less signals high risk of fog, low stratus, or rapid IMC development
• Legal VFR minimums and safe VFR minimums are not the same thing - build personal minimums with margin above the regulatory floor
• Read multiple consecutive METARs to understand trend, not just current conditions