METAR decoder

Model: WMO FM 15/16 METAR and SPECI as coded in the US under FAA Order JO 7900.5E, with its remarks; flight categories from the FAA Aviation Weather Handbook

Show your work

Every coded group of the report, and what it says.

KDEN

METAR for KDEN

181753Z

observed day 18 at 1753Z

30015G25KT

wind 300° true at 15 kt, gusting 25 kt

10SM

visibility 10 statute miles

FEW080

few at 8,000 ft

SCT200

scattered at 20,000 ft

30/08

temperature 30 °C, dew point 8 °C

A2980

altimeter 29.80 inHg

RMK

remarks follow

AO2

automated station with a precipitation discriminator (rain or snow)

SLP052

sea-level pressure 1,005.2 hPa

T03000083

precise temperature 30 °C, dew point 8.3 °C

Accuracy: Decodes the text as written. It does not check the report against the station or fetch anything.

When to use this: Use this when you have a METAR or SPECI in front of you and want it in words: the wind, visibility, present weather, clouds and the ceiling, temperature and dew point, the altimeter setting, the US remarks, and the flight category that follows from the ceiling and visibility. It is also a way to check your own reading of an unfamiliar group.

Limitations: It reads the report as written: it does not fetch anything, does not check the report against the station, and does not judge whether the weather is flyable. Winds in a METAR are true, not magnetic, which matters when you compare them with a runway. Groups it cannot read are listed rather than dropped, so an unexpected remark is visible rather than silently lost.

Worked example: Denver on a gusty afternoon. Source: add-practitioner-essentials weather scenario: 300° true at 15 gusting 25, 10 SM, FEW080 SCT200, 30.0/8.3 °C, 29.80 inHg, SLP 1005.2 hPa. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.

Review: Not yet independently reviewed by a flight instructor (CFI).

Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.1.1, core 0.1.0. See this tool in the verification report.

Changes

• 2026-09-23, fixed: An altimeter setting of A2980 showed as 29.8 inHg. Settings are given to hundredths (FAA-H-8083-28B section 24.4.3.11), so the METAR decoder and the QNH of the Q-codes tool now keep the trailing zero: 29.80 inHg. In hPa they read as before. The METAR decoder is now version 1.1.1 and the Q-codes tool 1.1.1. Changelog
• 2026-09-19, result change: Present weather now reads as the FAA Aviation Weather Handbook does, with intensity on the precipitation: +TSRA is "thunderstorm with heavy rain" (was "heavy thunderstorm rain"), +SHRA is "heavy rain showers", and VCSH is "showers in the vicinity". Tool versions 1.1.0. The METAR and winds-aloft decoders are now stable. Changelog
• 2026-09-19, fixed: A differential against python-metar on 612 live reports found three METAR defects, now fixed: cloud layers with /// (type not determined by an automated station) were dropped, BECMG and TEMPO trend groups were applied to the current observation (a forecast wind could replace the observed one), and 9999NDV visibility was not read. The winds-aloft decoder now accepts a whole pasted FB product and takes its levels from the FT header. Changelog

Checked against: 23 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

• Surface Weather Observing, FAA Order JO 7900.5E, Federal Aviation Administration, JO 7900.5E Change 1. Chapter 14 (METAR/SPECI coding) and Chapter 15 (remarks: AO1/AO2, SLP, T group, PK WND, WSHFT, PRESRR/PRESFR, $).
• Aviation Weather Handbook, FAA-H-8083-28B, Federal Aviation Administration, FAA-H-8083-28B. Section 8.4 (altimetry), section 3.4.2.14 and tables 3-17 and 3-18 (flight categories), section 24.4 (METAR and SPECI), section 27.2 (FB winds and temperatures aloft), and section 27.4 (TAF). Read free.

Terms

METAR: aviation routine weather report

An airport weather observation in a standard code: wind, visibility, weather, clouds, temperature, dew point, and altimeter setting, issued at least hourly. Source: Aviation Weather Handbook

UTC: Coordinated Universal Time

The world's civil time standard, kept within 0.9 s of Earth's rotation by leap seconds. Aviation calls it Zulu time, written with a Z. Source: IERS Bulletin C (leap seconds)