The METAR, the Remarks Section Nobody Reads, and the Station Observation That Tells You More Than Any Forecast Could

A METAR is an observation, not a forecast. It tells you what was happening at a specific airport at a specific moment, and when it diverges from the forecast, trust the METAR. Most pilots decode the main body and stop there - but the remarks section often contains the most operationally useful information in the entire report.

What Is a METAR and Where Does It Come From?

METAR stands for Meteorological Aerodrome Report - the initials come from the French, which is why they don’t match the English. It is a surface observation produced by an automated or staffed weather observing station at or near an airport. In the contiguous United States, these stations report every hour on the hour.

When conditions change significantly between hourly reports, a special observation called a SPECI is issued. A METAR is not a model output and not a probability - it is measured ground truth.

How Do I Read the Station Identifier and Time?

The first element is the four-letter station identifier. Contiguous 48 states start with K. Alaska uses PA. Canada uses C. If you’re briefing a cross-country into the Caribbean or Mexico, the format differs - know it before you brief.

The timestamp follows: day of month, then time in Zulu (UTC). Every METAR, TAF, and SIGMET in aviation uses Zulu time. If you’re not yet converting automatically, set a second clock on your phone to UTC and use it for every weather briefing until the conversion becomes second nature.

How Do I Decode Wind in a METAR?

Wind is reported as direction in degrees, then speed in knots, then gusts if present. 31012G22KT means wind from 310 degrees at 12 knots, gusting to 22.

A critical point many students miss: METAR wind directions are in degrees true, not magnetic. ATIS and tower read you magnetic. When comparing METAR winds to your ATIS at the runup area, a conversion is needed. In the central U.S. where magnetic variation is small, the difference may be 2–3 degrees. On the coasts or at high latitudes, it can be significant - and the checkride examiner may ask.

The gust factor is the difference between sustained wind and peak gust. A common technique: add half the gust factor to your Vref on final approach. In the example above, that’s 5 knots added to Vref. Some instructors use the full gust factor in turbulent conditions. Either way, do that math before you launch.

If wind is light and variable, you’ll see VRB in place of a direction. A variable wind range appended after the main report - 23015G22KT 200V270 - means the wind is swinging 70 degrees, and the favored runway may not stay favored.

What Does Visibility Mean in a METAR?

Visibility is reported in statute miles - not nautical miles, not kilometers. Ten statute miles is excellent. Three statute miles is legal VFR but leaves little margin. Below three miles is marginal VFR, working toward instrument meteorological conditions.

When visibility is below three miles, you’ll see it as a fraction: 1 1/2SM, 2 1/4SM. M1/4SM means less than one quarter of a statute mile - that airport is below VFR minimums.

RVR (Runway Visual Range) appears when conditions are low. It measures horizontal distance visible from the runway surface, in hundreds of feet, taken right at the threshold. R28L/4000FT/D means Runway 28 Left has an RVR of 4,000 feet with a decreasing trend. D = decreasing, U = increasing, N = no change. As a VFR pilot, RVR below 4,000 feet with a D trend means conditions are actively getting worse.

What Do Present Weather Codes Mean?

Present weather codes describe precipitation or obscuration. The most common:

• RA - Rain
• SN - Snow
• DZ - Drizzle
• FG - Fog (visibility below 5/8 mile)
• BR - Mist (visibility between 5/8 mile and 6 miles)
• HZ - Haze
• FU - Smoke

Intensity modifiers: a minus sign (-) means light, a plus sign (+) means heavy. +RA is heavy rain. -SN is light snow. TS before a code indicates thunderstorm - TSRA is thunderstorm with rain.

FZRA is freezing rain - ice forming on contact with surfaces. It is among the most dangerous icing conditions because accumulation is rapid and not always obvious from a distance.

One code every pilot should know cold: +FC means tornado or waterspout - the funnel has reached the surface. If you see +FC on a METAR at your destination, you’ve already missed the go/no-go decision. Make it before you ever see that code.

How Do I Interpret Cloud Layers and Ceilings?

Cloud coverage terms:

• SKC - Sky clear, reported by a human observer who confirmed nothing above 12,000 feet AGL
• CLR - Clear below 12,000 feet, reported by an automated station that cannot detect above that altitude
• FEW - 1/8 to 2/8 coverage
• SCT (Scattered) - 3/8 to 4/8 coverage
• BKN (Broken) - 5/8 to 7/8 coverage
• OVC (Overcast) - 8/8 coverage

The distinction between CLR and SKC is subtle but real. A CLR report says nothing about what may exist above 12,000 feet.

A ceiling is the lowest layer reported as broken or overcast. In a report showing FEW025 BKN040 BKN080, the ceiling is 4,000 feet AGL - the broken layer. The few layer at 2,500 feet is not a ceiling. Getting this wrong on a checkride is a common mistake.

CB after a cloud layer means cumulonimbus. TCU is towering cumulus. BKN030CB means broken cumulonimbus at 3,000 feet AGL - embedded thunderstorm activity directly over that airport. No forecast delivers that precision or timeliness.

What Does the Temperature/Dew Point Spread Tell Me?

Temperature and dew point are reported in degrees Celsius. The spread between them is one of the most practical numbers in a METAR.

A useful formula: take the temperature/dew point spread in Celsius, divide by 2.5, then multiply by 1,000. The result is a rough estimate of where low clouds will form in feet AGL. A spread of 9°C gives approximately 3,600 feet - close to the broken layer in a standard example.

When the spread drops below 3°C, fog or low clouds are likely, especially overnight or in early morning. Radiation fog forms when the ground cools and surface temperature drops to the dew point. An evening METAR showing a 2°C spread is a direct signal to check current conditions before loading the airplane for an early departure.

How Do I Set the Altimeter from a METAR?

The altimeter setting appears as a four-digit code: A2992 means 29.92 inches of mercury - standard sea level pressure. High pressure systems push the setting above 30.00. Low pressure brings it down toward 29.50 or lower.

The old saying applies: “From high to low, look out below.” Flying from high pressure into low pressure without updating the altimeter setting means the instrument reads higher than your actual altitude. Update at every stop and every ATIS check-in.

What’s in the METAR Remarks Section?

The remarks section begins with RMK. Most pilots stop reading here. Most of the interesting information is here.

AO1 vs. AO2

AO1 indicates an automated station without a precipitation discriminator - it knows precipitation is falling but cannot determine whether it is rain, snow, freezing rain, or sleet. AO2 has the discriminator and can distinguish. At an AO1 station in conditions where freezing precipitation is possible, you have less information than you might assume.

Sea Level Pressure (SLP)

Reported in hectopascals (millibars). Pull METARs from the same station across the past three hours and watch the SLP trend. Rising pressure generally means clearing. Falling pressure generally means deteriorating conditions. A change of 3 mb/hour is meaningful; 6 mb/hour is rapid change.

PRESRR and PRESFR

PRESRR (pressure rising rapidly) and PRESFR (pressure falling rapidly) appear when the system flags unusually fast change. PRESRR on a station with a broken ceiling and good visibility suggests improving conditions. PRESFR on a station already sitting at a broken ceiling is a reason to watch the next several reports carefully before launching.

Temperature to Tenths (T Field)

Reports temperature and dew point to the nearest tenth of a degree Celsius. For most VFR flying, this precision doesn’t change the decision. At high-elevation airports where density altitude matters, or when evaluating icing potential near 0°C, the tenth-degree resolution can matter.

Peak Wind (PKWND)

If the station recorded a gust stronger than anything in the main body during the past hour, it appears here with direction, speed, and the minute it occurred. PK WND 27038/43 means the wind peaked at 38 knots from 270 degrees, 43 minutes past the hour. A current wind of 12 gusting 22 after a recent peak of 38 means you need to decide whether you’re in a lull or watching a genuine trend. Pull the full METAR sequence and check PIREPs before deciding.

Precipitation Begin/End Times

Rain began at 15 past the hour and ended at 42 - one contained weather event that appears to be over. The next question is whether another cell is behind it. This is why you check radar alongside the METAR, not instead of it.

Lightning Observations

Staffed stations report lightning type and direction using LTG codes - cloud-to-ground, cloud-to-cloud, in-cloud. Staffed stations can detect lightning from many miles away. Automated stations often cannot. In convective conditions at an automated station, the remarks section may not capture lightning you can’t see. That’s when onboard datalink weather and radar pull the weight.

How Do I Use Multiple METARs Together?

One METAR is a snapshot. A series of METARs is a trend.

Pull METARs for your departure, destination, alternate, and reporting stations along the route. Look at them together. Watch the dew point spreads - narrowing spreads and temperatures dropping toward the dew point mean fog forming or low clouds building. Widening spreads mean conditions improving. Watch the altimeter settings - is pressure rising or falling along the route? Use that to confirm or challenge what the area forecast is telling you.

Read the remarks every time. PRESRR and PRESFR. PKWND if gusty conditions are a factor. Precipitation begin and end times. AO1 or AO2 when precipitation type matters.

What Does the Checkride Examiner Expect?

The Airman Certification Standards for the private pilot oral exam require a complete METAR decode - through the remarks section. The examiner will hand you a METAR and listen to how you work through it.

Specifically, expect to explain: what the dew point spread implies for cloud formation, the difference between CLR and SKC, what PRESFR means and why it matters, and what an AO1 station cannot tell you about precipitation type. If you stop at the altimeter setting, you’ve told half the story.

Key Takeaways

• A METAR is an observation, not a forecast. When the forecast diverges from the current METAR, trust the METAR.
• METAR winds are in degrees true; ATIS and tower read magnetic. Know the difference before your checkride.
• A ceiling is the lowest broken or overcast layer - a FEW or SCT layer below it is not a ceiling.
• A temperature/dew point spread below 3°C, especially in early morning, is a direct warning of fog or low cloud formation.
• The remarks section - AO1/AO2, SLP trend, PRESRR/PRESFR, PKWND, precipitation times - often contains the most operationally useful information in the report. Read all of it, every time.