METAR Remarks (RMK) Decoded

Updated: 2026-09-27 · First published: 2026-09-27 · About this site

The main body of a METAR is written for everyone. The remarks — everything after RMK — are written for people who want the numbers behind it: pressure to a tenth of a hectopascal, temperature to a tenth of a degree, the exact time the wind peaked, and what the station's sensors could and could not see. US and Canadian reports use remarks heavily; ICAO reports elsewhere use them sparingly. Either way, if a remark is there, it is there because the observer or the algorithm thought it mattered.

Station-type codes

AO1 / AO2 — automated station without / with a precipitation discriminator. AO2 can distinguish rain from snow; AO1 reports precipitation as unknown (UP).
AUTO in the body (not the remarks) — the whole report is automated with no human augmentation. Cloud is measured by a ceilometer looking straight up, so CB/TCU are not reported unless the station has a lightning sensor, and visibility is measured at one point.
RVRNO, PWINO, PNO, FZRANO, TSNO, VISNO, CHINO — a particular sensor is not available: runway visual range, present-weather identifier, precipitation amount, freezing-rain sensor, thunderstorm detection, visibility at a secondary location, cloud height at a secondary location. TSNO on a summer afternoon means the report cannot tell you there is a thunderstorm; look at the radar.
$ — the station needs maintenance. Treat every value with a little suspicion.

Pressure remarks

SLP — sea-level pressure, computed from station pressure using the actual temperature history rather than the standard atmosphere (which is what QNH uses). SLP132 is 1013.2 hPa. It is the value meteorologists plot on surface charts, and on a warm day it can differ from the QNH by a hectopascal or two. Never set it on the altimeter.

5appp — three-hour pressure tendency, reported at the synoptic hours (00, 03, 06 … UTC). The character digit a:

a	Tendency
0	Rising, then falling; now higher than 3 h ago
1	Rising, then steady
2	Rising steadily
3	Falling or steady, then rising faster
4	Steady
5	Falling, then rising; now lower than 3 h ago
6	Falling, then steady
7	Falling steadily
8	Rising or steady, then falling faster

58027 is a pressure that was rising or steady and is now falling quickly, down 2.7 hPa in three hours — the signature of an approaching front or a developing low. PRESRR and PRESFR (pressure rising / falling rapidly, at least 0.06 inHg per hour, about 2 hPa) are the same warning in plain words. The trend section of every station page on this site plots QNH over the previous days so the tendency is visible without decoding.

Temperature remarks

TsTTTsTdTdTd — T02171156 is +21.7 °C / −15.6 °C. The leading digit of each half is the sign. This is the value to use for the dew point spread when the body has rounded 21.5 to 22 and 21.4 to 21. 1sTTT / 2sTTT are the six-hour maximum and minimum (10256 = max 25.6 °C, 21017 = min −1.7 °C); 4s... is the 24-hour max/min at the end of the day.

Wind remarks

PK WND 24035/1347 — peak wind 240° at 35 kt at 13:47 UTC. Reported when the peak exceeded 25 kt since the last routine report. If the body says 24018G28KT and the remark says 35, the strongest gust of the hour was 7 kt above the reported gust; the gust in the body is the peak of the last ten minutes only.
WSHFT 1325 — wind shift at 13:25 UTC; WSHFT 1325 FROPA adds that it was a frontal passage.
WND DATA ESTMD — the anemometer is unserviceable and the wind was estimated.

Weather and cloud remarks

RAB25E40 — rain began at :25 and ended at :40 past the hour. TSB1310E1355 — thunderstorm began 13:10, ended 13:55. These answer "is the storm still here?" when the body still shows TS.
CB DSNT W, TCU OHD, VIRGA SW — cumulonimbus distant to the west (more than 10 miles), towering cumulus overhead, virga to the southwest. Human observers add these; automated stations cannot.
CIG 004V009 — the ceiling is varying between 400 and 900 ft. A ceiling of "BKN006" in the body with this remark is a ceiling that will be 400 ft on one approach and 900 on the next.
VIS 1/2V2 — visibility varying between ½ and 2 statute miles.
LTG DSNT ALQDS — lightning distant in all quadrants.
P0012 — 0.12 inches of precipitation in the last hour. 60025 — 0.25 inches in the last 3 or 6 hours. 4/012 — 12 inches of snow on the ground.

Recent weather and trend in ICAO reports

Outside North America, ICAO reports put two things after the main body that are not strictly remarks but are read the same way. RE groups — RETS, REFZRA — report recent weather that occurred in the last hour but not at the time of observation. A trend — NOSIG, BECMG 5000 BR, TEMPO TSRA — is a two-hour landing forecast attached to the observation, and it outranks the TAF for the next two hours because it was written later with the current sky in view. European reports such as EDDF Frankfurt or EGLL Heathrow carry a trend on almost every observation; when it says anything other than NOSIG, read it before you read the TAF.

How this site handles remarks

The decoder on every airport page recognises the US, Canadian, Russian and Chinese national remark groups and explains each one in place, with the source document it comes from (FMH-1 for the US groups, WMO No. 306 for the international ones). Tap any code in the raw report to see its meaning. Where a remark contradicts the body — a PK WND far above the reported gust, a CIG variation below the reported ceiling — the remark is the one to plan with.

Frequently asked questions

What does AO2 mean in a METAR?

An automated station with a precipitation discriminator — it can tell rain from snow. AO1 is an automated station without one. Both may be followed by additional automated codes such as RVRNO (RVR not available) or TSNO (thunderstorm detection not available).

What does SLP mean?

Sea-level pressure in hectopascals with the leading 9 or 10 omitted and the last digit in tenths. SLP132 is 1013.2 hPa; SLP998 is 999.8 hPa. Choose the leading digits that give a value closest to 1000. It is not the altimeter setting and must not be set on the altimeter.

What is the T group, e.g. T02171156?

Temperature and dew point to a tenth of a degree. The first digit of each four-digit block is the sign (0 positive, 1 negative). T02171156 is +21.7 °C and −15.6 °C. It is the source for the precise spread when the main body has rounded both to whole degrees.

What does PK WND 24035/1347 mean?

Peak wind since the last routine report: from 240° at 35 kt, occurring at 13:47 UTC. It is reported when the peak exceeds 25 kt. Compare it with the body wind to see how gusty the last hour really was.

What is the pressure tendency group 5xxxx?

A five-digit group beginning with 5: the second digit is the tendency character (0–3 rising, 4 steady, 5–8 falling), the last three are the change over three hours in tenths of a hectopascal. 52012 means rising then steady, +1.2 hPa in three hours; 57025 means falling, −2.5 hPa.