Inside METAR Remarks: SLP, PK WND, and the T Group

Everything after RMK in a US METAR is the remarks section, and it is where the report stops rounding. The remarks section carries precise data, where SLP110 is a sea-level pressure of 1011.0 hPa and T02940111 gives temperature and dewpoint to a tenth of a degree. The body of the METAR rounds temperature to whole degrees and reports an altimeter setting; remarks add the finer numbers that observers, forecasters, and trend analysis actually need. Paste any report into wxdecoder and the remarks expand into labeled lines, but the codes follow fixed rules you can read by hand.

This guide is part of the METAR field guide. It walks the common US remarks in the order they usually appear: station type, peak wind, wind shift, sea-level pressure, hourly precipitation, the precise T group, the 6-hour and pressure-tendency groups, and thunderstorm timing.

Station type: AO1 and AO2

Remarks almost always open with the automation flag. AO1 means an automated station with no precipitation discriminator: it measures wind, visibility, and pressure but cannot distinguish rain from snow. AO2 means an automated station that does have a precipitation discriminator and can identify type. A trailing $ anywhere in remarks means the station has flagged itself for maintenance. These flags, plus AUTO and COR in the body, are covered in depth in AO1, AO2, AUTO, and the maintenance flag.

Peak wind: PK WND dddff/hhmm

PK WND records the highest instantaneous wind since the last routine report. The format packs direction, speed, and a timestamp into one token:

PK WND 27045/1532

The digits before the slash are direction and speed in the same convention as the body wind group: 270 is 270 degrees true, 45 is 45 knots. The digits after the slash are the time of the peak. When only four digits follow the slash they are the hour and minute, so 1532 is 1532 Zulu. A peak wind well above the sustained value in the body is a flag for gusty, convective, or frontal conditions. For how the body wind group rounds and reports gusts, see reading the METAR wind group.

Wind shift: WSHFT

WSHFT followed by a time marks a wind shift, a sudden change in direction often tied to a frontal passage or thunderstorm gust front. WSHFT 1715 means the shift occurred at 1715 Zulu. If a frontal passage caused it, you may see WSHFT 1715 FROPA.

Sea-level pressure: SLPppp

The body of a US METAR gives an altimeter setting in inches of mercury, such as A2992. Remarks add the actual sea-level pressure in hectopascals, encoded in three digits after SLP. The decode rule has two steps:

1. Prepend a 9 or a 10 so the result lands near 1000 hPa.
2. Divide by 10.

So SLP110 becomes 1011.0 hPa, because 110 with a leading 10 is 1011, divided by 10. A lower-looking value like SLP984 becomes 998.4 hPa, because 984 with a leading 9 is 9984, divided by 10. The choice between 9 and 10 is always whichever lands closest to 1000, which is why both directions of the rule produce a realistic pressure.

Sea-level pressure and the altimeter setting answer different questions: the altimeter is what you dial into the Kollsman window, while SLP is a meteorological value for charting and trends. For the body pressure group, see A2992 is pressure, not temperature.

Hourly precipitation: P####

A P followed by four digits is the precipitation accumulated since the last hourly report, in hundredths of an inch. P0009 is 0.09 inch; P0125 is 1.25 inch. P0000 means a trace was measured but rounded to zero accumulation in this period.

The T group: precise temperature and dewpoint

The body of the METAR reports temperature and dewpoint to whole degrees, such as 29/M11. The T group sharpens that to a tenth of a degree Celsius. It is one token, a T followed by eight digits, split into two four-digit blocks:

T02940111

The first digit of each block is the sign: 0 is positive, 1 is negative. The remaining three digits are degrees and tenths.

• First block 0294: sign 0 (positive), value 294, so temperature is +29.4 C.
• Second block 0111: sign 1 (negative), value 111, so dewpoint is -11.1 C.

That extra precision matters most when the temperature-dewpoint spread is small, because a spread of a few tenths near freezing is the difference between clear and fog or icing. For why that spread drives risk, see the M in M04 and why dewpoint spread matters.

The 6-hour and pressure-tendency groups

Three more numeric groups appear at the synoptic hours. Each begins with a fixed leading digit that identifies the group:

For the temperature groups, the digit after the leading 1 or 2 is the sign (0 positive, 1 negative) and the rest is tenths of a degree, mirroring the T group. The pressure-tendency group 5xxxx reports how the barometer moved over the last three hours: the digit after the 5 codes the shape of the change (rising, falling, steady) and the rest is the amount in tenths of a hectopascal. A falling tendency is an early hint of an approaching system even before the body pressure looks low.

Thunderstorm timing: TSB and TSE

When a thunderstorm starts or ends, remarks log the minute. TSB is thunderstorm begin and TSE is thunderstorm end, each followed by a time. TSB24 means the storm began at 24 minutes past the hour; a fuller form like TSB0159E24 records a begin and an end in one entry. These timing notes let a forecaster reconstruct the convective sequence at the field even after the storm has moved on.

A worked decode

Put the common codes together. Here is a realistic remarks tail:

RMK AO2 PK WND 27045/1532 SLP110 T02940111

• AO2: automated station with a precipitation discriminator.
• PK WND 27045/1532: peak wind 45 knots from 270 degrees true, at 1532 Zulu.
• SLP110: sea-level pressure 1011.0 hPa.
• T02940111: temperature +29.4 C, dewpoint -11.1 C.

Read in plain language: an automated field logged a 45-knot peak from the west at 1532Z, a sea-level pressure just above standard, and a hot, dry airmass with about a 40-degree spread between temperature and dewpoint. None of that precision survives in the rounded body of the report, which is the whole point of remarks.

Decode the whole tail at once

Remarks reward a consistent habit: read the leading token, apply its fixed rule, and move to the next. SLP prepends 9 or 10 and divides by 10; the T group reads each block as sign plus tenths; PK WND and WSHFT carry a Zulu time you can convert with the Zulu time guide. When you would rather have it read for you, paste the raw METAR into wxdecoder and every remark expands into a labeled line next to the original text. wxdecoder is for situational awareness, not an official briefing.

Last updated June 29, 2026