Reading a METAR
A field-by-field decode of a routine aviation weather report, plus the standard atmosphere every pilot must carry in their head.
A METAR (from the French Météorologique Aviation Régulière) is a coded routine observation of surface weather at an airport. The code is terse by design — every character carries information, and every pilot must be able to decode it without a reference.
Field by field
| Group | Meaning |
|---|---|
| KMKE | Milwaukee Mitchell International — station identifier |
| 141453Z | 14th of the month, 14:53 UTC |
| 27012G18KT | Wind from 270° at 12 knots, gusting to 18 |
| 10SM | Visibility 10 statute miles |
| FEW045 | Few clouds at 4,500 ft AGL |
| BKN080 | Broken layer at 8,000 ft AGL — ceiling |
| 22/14 | Temperature 22°C, dew point 14°C |
| A2992 | Altimeter setting 29.92 in Hg |
| RMK AO2 SLP132 | Automated station w/ precip discriminator, SLP 1013.2 hPa |
Temperature-dew point spread
The gap between temperature and dew point predicts visible moisture. When the spread closes to within about 2–3°C, expect fog, mist, or low stratus. The spread in the sample above is 8°C — comfortable margin.
The standard atmosphere behind the numbers
Every altimeter setting, every density-altitude calculation, and every performance chart is anchored to the International Standard Atmosphere (ISA): 29.92 in Hg and 15°C at sea level, with pressure decreasing about 1 in Hg per 1,000 ft and temperature decreasing about 2°C per 1,000 ft in the troposphere.
| Altitude | Pressure | Temperature |
|---|---|---|
| Sea level | 29.92 in Hg | +15°C |
| 2,000 ft | 27.82 in Hg | +11°C |
| 5,000 ft | 24.90 in Hg | +5°C |
| 10,000 ft | 20.58 in Hg | −5°C |
| 18,000 ft | 14.94 in Hg | −21°C |
Once you can read a METAR, the natural next step is a Meteorology hub deep-dive on TAFs and the aviation forecast products. For how these numbers reach the cockpit instruments, see The Pitot-Static System.
Educational content, not flight instruction. Consult a certificated flight instructor and current official publications.
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