The METAR Remarks Section, the RMK Line Most Student Pilots Skip, and the Automated Station Data That Can Change a Go Decision

Most pilots decode the main body of a METAR and move on. The remarks section - everything after RMK - contains rate-of-change data, sensor reliability flags, and precipitation precision that the main body simply cannot provide. Reading only half a METAR means making decisions with half the available information.

What Is the METAR Remarks Section?

The METAR (Meteorological Aerodrome Report) is an aviation routine weather observation - a snapshot of current conditions at a specific airport at a specific moment. It updates every hour at most automated stations and every 30 minutes at busier airports.

The main body follows a fixed coded format: station identifier, date/time in Zulu, wind, visibility, present weather, sky condition, temperature/dewpoint, and altimeter setting. Most ground school training covers this portion well.

After the altimeter setting, the letters RMK mark the beginning of the remarks. Here, the METAR shifts from a purely formatted coded sequence into a mix of standardized codes and plain-language observations - and the data quality and operational relevance increase significantly.

AO1 vs. AO2: Why Station Type Is the First Thing to Check

The first item after RMK is typically AO1 or AO2. This identifies the type of automated weather observing system that generated the report, and it directly affects how much you can trust the present weather group.

AO1 stations lack a precipitation discriminator. The system can detect that precipitation is occurring but cannot determine what type. It cannot distinguish rain from freezing rain, or drizzle from sleet. When an AO1 station reports “light rain,” that identification is an approximation - not a confirmed measurement.

AO2 stations have a precipitation discriminator and can identify precipitation type. The vast majority of automated stations in the contiguous United States are AO2. But in marginal temperatures - particularly in the shoulder seasons when surface temperatures hover near 0°C - the distinction matters enormously. An AO1 report in those conditions means your precipitation type is an educated guess, and icing exposure is unconfirmed.

This is a common instrument checkride oral question. More importantly, it’s a real-world decision factor when flying toward marginal conditions.

How Do Peak Winds in the Remarks Differ from the Main Body Wind?

The wind reported in the main body of a METAR is a 10-minute average. It reflects steady-state conditions at the moment of observation.

The peak wind remark - coded as PK WND followed by direction, speed, and a four-digit Zulu time - records the highest instantaneous gust observed in the past hour. For example:

PK WND 24028/1731 means the peak wind was from 240° at 28 knots at 1731Z.

If the main body shows winds at 12 gusting 22, but the peak wind in the past hour was 28, the air mass has already demonstrated it can produce gusts well above the current average. That doesn’t guarantee a repeat. But it means 22 knots is not the ceiling on what this environment can generate, and your approach planning should reflect that.

The main body is an average. The peak wind is a sample of what the atmosphere is actually doing. Both numbers belong in your analysis.

What Does a Wind Shift in the Remarks Tell You?

The code WSHFT followed by a Zulu time indicates that the wind direction shifted significantly at that moment. For example, WSHFT 1715 means the wind changed direction at 1715Z.

A wind shift observed in the last 30 minutes raises an immediate question: is the active runway still the correct runway? Frontal passages almost always register in the remarks as a wind shift before the main body conditions have stabilized to reflect new steady-state winds.

The remarks give you the annotation. The main body gives you the current average. Together, they reveal a surface that has recently been through something - and that context changes how you interpret everything else in the observation.

How to Read Sea Level Pressure in the METAR

Sea level pressure appears as SLP followed by three digits. The decode convention:

• If the resulting three-digit number is less than 500, prepend 10. So SLP098 = 1009.8 mb.
• If it is 500 or greater, prepend 9. So SLP982 = 998.2 mb.

For routine VFR operations, this is mostly background data. For instrument flight across routes with significant pressure gradients, tracking sea level pressure helps you anticipate altimeter changes and understand expected winds aloft before you dial in a new setting.

Why the Temperature Group Matters in Marginal Conditions

The main body reports temperature and dewpoint rounded to whole degrees Celsius. The temperature group in the remarks - coded as T followed by eight digits - provides one decimal place of precision.

For example, T01720150 decodes as a temperature of 17.2°C and a dewpoint of 15.0°C.

That tenth of a degree rarely changes a decision. But in marginal conditions near the dewpoint, it can. If the main body rounds and shows a zero spread, it may look like fog is at the surface. The precise values might show 2.4°C and 1.8°C - a small spread, but not as severe as the rounded numbers implied. The reverse is equally possible: a small perceived cushion that the precise values eliminate entirely.

How to Interpret Precipitation Amount

Precipitation amount is coded as P followed by four digits. P0012 means 0.12 inches of precipitation fell at this station in the past hour.

The operational value is runway and braking condition. If you’re arriving behind a weather system with visibility still reduced in rain:

• 0.01 inches/hour = drizzle. Wet runway, nothing more.
• 0.38 inches/hour = significant rainfall. Potential for standing water, compromised braking, hydroplaning risk.

Same visibility reduction on two different METARs can mean very different runway conditions. The precipitation amount is what distinguishes them.

What PRESRR and PRESFR Mean for Your Flight

PRESRR (pressure rising rapidly) and PRESFR (pressure falling rapidly) indicate a pressure change of at least 2 millibars in less than 2 hours - a significant rate.

PRESRR following a wind shift typically signals that a cold front has passed and a high-pressure system is building behind it. Conditions are likely improving.

PRESFR ahead of an approaching system is a warning. Something significant is moving toward that station at a pace already registering in surface pressure data. If you see PRESFR in the remarks, go back to the radar, the prog chart, and the TAF. The pressure data is telling you something is approaching faster than the main body conditions reflect.

This is what the remarks section does that the main body cannot: it provides rate-of-change information. The main body is a snapshot. The remarks are a one-hour record of what the station has experienced.

Lightning Codes in Automated METARs

Automated stations record detected lightning with specific type codes:

• LTGCG - cloud-to-ground
• LTGCC - cloud-to-cloud
• LTGIC - in-cloud

These codes are often followed by distance and direction. LTGCG DSNT NW means cloud-to-ground lightning detected, distant, to the northwest.

Distant lightning in the remarks is not clearance to proceed in that direction. It is a data point confirming that an active system exists in that quadrant. The question it sends you to answer - on radar, not in the METAR - is whether that system is stationary, moving away, or tracking toward you.

The Dollar Sign: The Most Important Flag You May Have Never Noticed

If a $ (dollar sign) appears at the very end of a METAR, the automated observing system has flagged itself as requiring maintenance. Something in the system is not operating correctly.

The report continues to transmit whatever the working sensors detect. But you don’t know which sensors are degraded or missing. The precipitation sensor, ceilometer, or visibility sensor may be reporting inaccurately.

When you see the dollar sign, treat the METAR the way you’d treat an AO1 report in marginal conditions: you have partial information. Cross-reference with nearby stations, PIREPs, and satellite imagery. The maintenance flag doesn’t disqualify the METAR - but it means the data requires corroboration before you act on it.

Putting It Together: A Complete METAR Reading

Consider this METAR for a destination:

Main body: Winds 230° at 12 gusting 22. Visibility 7 miles in light rain and mist. Broken at 800 feet, overcast at 1,500 feet. Temperature 17, dewpoint 15. Altimeter 29.82.

Remarks: AO2. PK WND 24028/1731. WSHFT 1715. SLP098. P0012. T01720150. PRESRR. $

Read only the main body, and you have a marginal picture - broken at 800, gusting to 22. A genuine decision point.

Read the remarks, and the picture shifts:

• AO2 confirms the light rain identification is sensor-verified.
• Wind shift at 1715Z and PRESRR together indicate a frontal passage roughly 15 minutes before the observation. The front has moved through.
• Peak wind of 28 knots means the boundary layer is still unsettled despite the improving trend.
• P0012 confirms the precipitation was real but not heavy - runway condition is wet, not compromised.
• T01720150 shows a 2.2°C spread - no immediate fog risk.
• $ means you cross-reference the ceiling with nearby stations before trusting it completely.

The trend is likely improving conditions. But the peak wind and maintenance flag mean you don’t treat the main body as the full picture.

That is a fundamentally different analysis than stopping at the altimeter setting.

The Two-Pass Habit

Every METAR, every time:

1. First pass: Decode the main body. Get the basic picture - wind, visibility, ceiling, temperature spread, altimeter.
2. Second pass: Read the remarks. Look for anything that changes or complicates that picture. Station type, peak wind, wind shift, pressure tendency, precipitation amount, lightning, and always check for the dollar sign at the end.

The full METAR decode reference is available at aviationweather.gov. The FAA Pilot’s Handbook of Aeronautical Knowledge and the Aviation Weather Services Advisory Circular both cover METAR decoding and are worth reviewing alongside the official reference.

Key Takeaways

• AO1 stations cannot distinguish precipitation type - in near-freezing temperatures, that means your icing exposure is unconfirmed.
• The main body wind is a 10-minute average; the PK WND remark shows the peak gust in the past hour and sets the actual upper bound on what the environment produced.
• WSHFT indicates a recent wind direction change - verify runway alignment before arrival.
• PRESRR and PRESFR provide rate-of-change information the main body cannot: a cold front passage or an approaching system already registering in surface pressure.
• A dollar sign ($) at the end of a METAR means the observing system requires maintenance - corroborate all values with nearby stations, PIREPs, and imagery before acting on them.