The METAR, the Cryptic String Students Learn to Decode, and the Remarks Section Nobody Teaches

A METAR (Meteorological Aerodrome Report, or Aviation Routine Weather Report in U.S. usage) is a standardized observation of actual conditions at an airport at a specific moment in time. It is not a forecast. The International Civil Aviation Organization (ICAO) defines the format globally, which means the METAR structure you learn for an airport in Ohio applies identically to airports in Germany or Australia.

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

The most common conceptual mistake student pilots make is treating a METAR like an all-clear signal. A METAR captures what sensors recorded - or what a human observer saw - at the moment of the observation. It says nothing about conditions at your current position, or what you will find when you arrive.

That role belongs to the Terminal Aerodrome Forecast (TAF). METARs and TAFs are complementary products. Neither one alone tells the whole story of a flight.

How Do I Read a METAR Field by Field?

The example decoded throughout this article:

KBDL 221855Z 23014G22KT 5SM -RA BR BKN018 OVC060 12/10 A2989 RMK AO2 SLP126 P0005 T01220100

Station Identifier

KBDL is the ICAO identifier for Bradley International Airport near Hartford, Connecticut. In the contiguous United States, all identifiers begin with K. KORD is Chicago O’Hare; KLAX is Los Angeles. International identifiers follow regional prefixes - CYYZ is Toronto, EGLL is London Heathrow.

Observation Time

221855Z means this observation was recorded on the 22nd day of the month at 1855 Coordinated Universal Time (Zulu). Routine observations are issued hourly. Always check the timestamp - a two-hour-old METAR may not reflect current conditions, and weather can change significantly in that window.

How Do I Decode Wind in a METAR?

23014G22KT breaks down as:

• Direction: 230° magnetic - wind from the southwest
• Sustained speed: 14 knots
• Gust: 22 knots - the maximum in the previous ten minutes

If wind direction is variable and light, you will see VRB instead of a three-digit heading. Calm wind appears as 00000KT.

A gust spread greater than ten knots is worth flagging. In this example the spread is eight knots (14 gusting to 22). Expect wind variations on final approach that affect crosswind correction and airspeed management. It is not a no-go, but it demands attention before you reach the runway.

What Does METAR Visibility Mean for VFR Flight?

5SM is five statute miles. In the United States, METAR visibility is reported in statute miles, with fractions used below seven miles when necessary (1/4 SM, 1-3/4 SM, etc.). The maximum reported value is 10SM - actual visibility may be greater, but the METAR does not go above ten.

Five statute miles is Marginal VFR (MVFR). The MVFR range spans 3 to 5 miles visibility and 1,000 to 3,000 feet ceiling. The color codes on weather apps map directly to these ranges - knowing the underlying numbers is what lets you evaluate those colors accurately.

How Do I Read Present Weather Codes?

-RA BR decodes as light rain and mist. The intensity modifier convention:

• – = light
• + = heavy
• No sign = moderate

Common weather codes: RA = rain, BR = mist, FG = fog, TS = thunderstorm, DZ = drizzle, SN = snow. The complete table is in the Aeronautical Information Manual (AIM) - have it memorized before your checkride.

Mist and fog are distinct and matter for minimums. Mist (BR) reduces visibility to between 5/8 mile and 6 miles. Fog (FG) reduces visibility below 5/8 mile. Seeing FG on a METAR indicates serious conditions.

How Do I Determine Ceiling and VFR Legality from Sky Condition?

Sky condition is reported in layers from lowest to highest. Coverage is measured in eighths of the sky:

• FEW = 1–2 eighths
• SCT (Scattered) = 3–4 eighths
• BKN (Broken) = 5–7 eighths
• OVC (Overcast) = all 8 eighths

For VFR flight, only broken and overcast layers constitute a ceiling. Few and scattered do not.

In this example, BKN018 OVC060 means broken at 1,800 feet AGL and overcast at 6,000 feet AGL. The ceiling is 1,800 feet - below the 1,000-foot VFR minimum. This airport, at this moment, is IFR.

If you see CB (cumulonimbus) or TCU (towering cumulus) appended after an altitude, treat it seriously. These convective clouds carry significant updrafts, turbulence, icing potential, and lightning. A broken layer at 3,000 feet marked CB is an entirely different situation from an ordinary broken layer.

What Do Temperature, Dewpoint, and Altimeter Setting Tell Me?

12/10 = temperature 12°C, dewpoint 10°C. A2989 = altimeter 29.89 inHg.

Two critical takeaways from temperature and dewpoint: the spread indicates proximity to saturation. When temperature and dewpoint are equal, relative humidity is 100 percent. The two-degree spread in this example is extremely narrow. A two-degree temperature drop - which commonly occurs after sunset - can produce fog. This single data point can change a go/no-go decision for an evening return flight.

Temperature also feeds density altitude calculations. The METAR reports in Celsius. Know the reference points: 0°C = 32°F, with each degree Celsius equal to approximately 1.8°F.

For the altimeter, standard atmosphere is 29.92 inHg. This example is slightly below standard, meaning pressure is a touch low. Failing to update your altimeter would place you slightly lower than your indicated altitude. Update whenever you receive a new ATIS or check in with approach control.

What Does the METAR Remarks Section Actually Contain?

Everything after RMK is the remarks section - and it holds some of the most operationally useful data in the entire observation. Most student pilots skip it. Most examiners notice.

AO1 vs. AO2: What Type of Station Issued This Report?

AO2 identifies an automated station with a precipitation discriminator. The discriminator can distinguish rain from snow from freezing rain. An AO1 station has no discriminator - it detects that something is falling, but cannot identify what.

If you are assessing icing risk and the station shows AO1, the automated equipment cannot confirm whether precipitation is freezing. Supplement with a PIREP (pilot report) or human observer data.

SLP: What Is Sea Level Pressure?

SLP126 = sea level pressure 1012.6 hPa. The METAR omits leading digits for brevity. To decode: for three-digit codes below 500, prepend “10” and insert a decimal before the last digit; for codes 500 and above, prepend “9”. SLP126 → 1012.6 hPa. SLP998 → 999.8 hPa.

Meteorologists use this number to track pressure systems. It is the figure a flight service briefer references when discussing an approaching high or low.

P: What Does the Precipitation Code Mean?

P0005 = 0.05 inches of precipitation in the past hour. This is accumulation data that helps gauge rainfall intensity. A high figure means it has been raining actively; a near-zero figure despite low ceilings may suggest improving conditions.

T: What Is the Precision Temperature and Dewpoint?

T01220100 = temperature 12.2°C, dewpoint 10.0°C - more precise than the whole-degree values in the METAR body. Useful for careful density altitude calculations and for monitoring a tight temperature-dewpoint spread when fog formation is a concern.

What Other Remarks Should I Know?

Rapidly changing pressure signals approaching weather regardless of direction. Cloud-to-ground lightning (LTGCG) in the remarks is not a nuance to weigh - it is a no-go for VFR near that location. TSB and TSE times help you determine whether a storm is building or dissipating.

How Do I Use Multiple METARs for a Complete Weather Briefing?

A single METAR is a snapshot. A series of METARs is a trend line. Compare the current observation against reports from one and two hours prior:

• Is visibility improving or degrading?
• Is the ceiling rising or lowering?
• Is the temperature-dewpoint spread narrowing?

A trend line tells you where the weather is going. In a full preflight briefing, read METARs for your departure airport, destination, alternates, and airports along your route. The trend across all of them reveals what a single observation cannot.

What Will a Checkride Examiner Ask About METARs?

The Airman Certification Standards (ACS) require you to demonstrate the ability to decode METARs and apply them to preflight planning. An examiner is not just checking that you can identify ceiling and visibility. Expect questions that include:

• Calculate the wind component for the runway in use
• Determine whether conditions are VFR, MVFR, or IFR and explain why
• Identify what a specific remark tells you about the observation source

The most common checkride mistake on this topic: reading the METAR body correctly, then ignoring the remarks. It happens consistently enough that examiners watch for it.

Weather briefing is a habit built through repetition, not a skill activated only when conditions look questionable. Reading the full METAR carefully on clear-sky days is how you build speed and accuracy for the days when it matters most.

Key Takeaways

• A METAR is an observation of current conditions at a specific moment, not a forecast - pair it with the TAF for a complete picture.
• Only broken and overcast layers constitute a ceiling. BKN018 means the ceiling is 1,800 feet AGL - IFR conditions.
• A temperature-dewpoint spread of 2°C or less signals imminent fog risk, particularly after sunset.
• AO1 stations cannot distinguish precipitation type. Supplement with PIREPs when icing is a concern.
• The remarks section contains precision temperature, precipitation accumulation, pressure trends, and lightning data absent from the METAR body - read it every time.