How to Read METAR Remarks (RMK)

Everything after the RMK keyword is the remarks section. It carries some of the most useful detail in the whole report — precise pressure and temperature, how the wind is behaving, and what the weather has done recently — but it is written in a dense shorthand. This guide walks through the remarks you will actually see, one group at a time, so you can read them without a lookup table.

A full example

KORD 121651Z 18009KT 10SM FEW250 24/17 A3002
RMK AO2 SLP163 T02440167 10267 20233 58012 PK WND 20028/1625

The body ends at A3002. From RMK onward, each group is decoded below. Note that not every station reports every group, and the order can vary slightly.

Station type: AO1 and AO2

AO1 means the station is automated without a precipitation discriminator — it can detect precipitation but not whether it is liquid or frozen. AO2 means the station is automated witha precipitation discriminator, so it can distinguish rain from snow. Almost all U.S. automated stations reportAO2.

Sea-level pressure: SLP

SLP163 gives the sea-level pressure to the nearest tenth of a hectopascal (millibar). Prefix the value with 10 or 9 — whichever brings it closest to 1000 — and insert a decimal before the last digit. So SLP163 is 1016.3 hPa, and SLP995 would be999.5 hPa. This is more precise than the altimeter setting in the body and is the value used for surface-analysis charts.

Precise temperature: the T-group

The body reports temperature and dew point in whole degrees Celsius. The T group in remarks gives the same values to the nearest tenth of a degree. Read it as T then two four-digit blocks: the first digit of each block is the sign (0 = positive, 1 = negative), followed by the value in tenths.

So T02440167 is a temperature of 24.4 °C and a dew point of 16.7 °C — more precise than the 24/17 shown in the body. A leading 1 flips the sign: T10120033 is −1.2 °C over −3.3 °C.

6-hour and 24-hour temperature extremes

Groups beginning 1 and 2 report the 6-hour maximum and minimum temperature; 4reports the 24-hour maximum and minimum. In the example, 10267 is a 6-hour maximum of 26.7 °C and20233 is a 6-hour minimum of 23.3 °C. As with the T-group, the digit after the leading indicator is the sign.

Pressure tendency: the 5-group

A group beginning with 5 describes how the barometric pressure has changed over the past three hours.58012 breaks down as: 5 (tendency group), 8 (the character of the change), and 012 (the amount, 1.2 hPa). The character digit runs 0–8: values 0–3 mean pressure is now higher than three hours ago, 4 means unchanged, and 5–8 mean it is now lower. A steadily falling barometer often signals approaching weather.

Peak wind and wind shift

• PK WND 20028/1625 — peak wind: the maximum instantaneous gust since the last report was from 200° at 28 knots, recorded at 1625Z.
• WSHFT 1615 — a wind shift occurred at 1615Z. If it was frontal, it readsWSHFT 1615 FROPA.

Variable visibility and variable ceiling

• VIS 3/4V1 1/2 — prevailing visibility is varying between 3/4 and 1½ statute miles.
• CIG 008V012 — the ceiling is variable between 800 and 1,200 ft.

Precipitation and weather timing

• RAB05E42 — rain began at :05 and ended at :42 past the hour.
• P0009 — 0.09 inches of precipitation in the past hour.
• 6 and 7 groups report 3/6-hour and 24-hour precipitation totals respectively.
• TSB25E50 — a thunderstorm began at :25 and ended at :50.

Other common remarks

• PRESRR / PRESFR — pressure rising or falling rapidly.
• LTG — lightning, often with location, e.g. LTG DSNT W (distant lightning to the west).
• CB DSNT NE — cumulonimbus cloud in the distance to the northeast.
• NOSIG — no significant change expected in the next two hours.
• $ — the station needs maintenance; data may be suspect.

The full example, group by group

Applying everything above to the remarks in our opening example:

Pressure remarks in depth

Remarks carry the most precise pressure information in the report. Beyond SLP, the codes PRESRR and PRESFR flag pressure rising or falling rapidly — typically more than about 0.06 inches of mercury in the 15 minutes before the observation — which often accompanies a passing front. The 3-hour tendency group (beginning with 5) then gives both the amount and the character of the change: whether the pressure rose then fell, fell steadily, or held steady before moving. Read together, these describe what the atmosphere is doing in a way a single altimeter setting cannot.

Precipitation timing and amounts

Automated stations log when precipitation starts and stops. RAB05E42 means rain began at 5 past and ended at 42 past the hour, and several begin/end pairs can be chained on a showery day. Amount groups follow: P0009 is hundredths of an inch in the past hour (0.09 in), a 6-group gives the 3- or 6-hour total, and a 7-group the 24-hour total. These figures matter for runway condition and for judging how fast things are changing.

More remark groups you may meet

• SNINCR 2/10 — snow increasing rapidly: 2 inches in the past hour, 10 inches total on the ground.
• 4/021 — snow depth on the ground is 21 inches.
• GR 1 3/4 — largest hailstone was 1¾ inches in diameter.
• I1002 — ice accretion: 0.02 in of ice in the past hour.
• VIRGA — precipitation seen falling but evaporating before it reaches the ground.
• TS OHD MOV E — thunderstorm overhead moving east (a human-written remark).

Automated versus manual remarks

Fully automated stations can report pressure, temperature, precipitation timing, and peak wind on their own, but they cannot describe cloud type, distant weather, or anything that needs a human eye. Staffed stations add plain observations such as ACSL SW (a standing lenticular altocumulus to the southwest) or a note that a thunderstorm is moving through. If a remark reads almost like a sentence, a person probably wrote it.

Common mistakes

• Reading the T-group sign digit as part of the value — the leading 0 or 1 is only the sign.
• Forgetting to insert the decimal in SLP, or prefixing with 9 instead of 10 when the value is near 1000 hPa.
• Confusing the 6-hour max/min (1 and 2 groups) with the 24-hour extremes (4 group).
• Assuming every station reports every group — availability varies widely by station and country.

Limitations

Remarks are supplementary and their availability varies by station and country. Automated sites omit human-only remarks, and some coded groups are region-specific. Treat remarks as helpful context, not as a replacement for a full briefing. For the body of the report, see How to Read a METAR.

Official sources

• FAA Aviation Weather Handbook (FAA-H-8083-28).
• NWS Federal Meteorological Handbook No. 1 (FMH-1), Surface Weather Observations and Reports.
• NWS Aviation Weather Center — aviationweather.gov.