Weather forecasts tell you what conditions are expected. METARs tell you what conditions actually are right now, measured at a real weather station at the nearest airport. For drone pilots, that difference matters, and learning to read a METAR takes about ten minutes.
Here is a complete breakdown of every field you will encounter.
What a METAR Is
METAR stands for Meteorological Aerodrome Report. It is a standardized weather observation issued every hour (and sometimes more frequently as conditions change) by automated or human observers at airports worldwide. The format is the same everywhere; a METAR from LAX reads exactly like one from a small regional airport.
METARs are the most reliable source of current conditions near your flight location. Forecast models have error margins. METARs are measured observations. When a forecast says 8 mph winds and the METAR says 22 mph gusting 34, you fly with the METAR.
A Sample METAR
Here is a real METAR. We will decode it field by field:
METAR KDEN 191753Z 27018G28KT 10SM FEW035 BKN080 OVC150 14/02 A2987 RMK AO2 SLP112
Field-by-Field Breakdown
Report type: METAR or SPECI
METAR is a routine hourly report. SPECI is a special observation issued when conditions change significantly between hourly reports: a sudden drop in visibility, a wind shift, or the onset of precipitation. If you see SPECI, conditions changed fast enough that the automated system issued an unscheduled report.
Station identifier: KDEN
The four-letter ICAO identifier for the reporting station. US stations start with K (KDEN = Denver International). Alaska stations start with PA, Hawaii with PH. Puerto Rico with TJ, Guam with PG.
Date and time: 191753Z
Day of month followed by time in UTC (Zulu). 191753Z means the 19th of the month at 17:53 UTC. METARs are always in UTC; convert to local time for practical use. METAR data older than 60 minutes is stale; older than 90 minutes is unreliable.
Wind: 27018G28KT
Direction in degrees true (270 = west), speed in knots (18 kt), gust in knots (G28 = gusting to 28 kt). To convert knots to mph, multiply by 1.15. So 18G28KT = 21 mph sustained, gusting to 32 mph.
VRB means variable direction: wind is shifting more than 60 degrees. Common in light and variable conditions, and a turbulence indicator even at low speeds.
00000KT means calm (no wind). A group like 27018G28KT 240V310 means the wind is varying between 240 and 310 degrees at that speed, significant directional instability.
Visibility: 10SM
Prevailing visibility in statute miles. 10SM is the maximum reportable value and means 10 miles or greater. Part 107 requires a minimum of 3 statute miles (14 CFR 107.51). Values below 3SM are a hard no-go for standard Part 107 operations.
P6SM means greater than 6 statute miles. M1/4SM means less than 1/4 mile, effectively zero visibility.
Sky condition: FEW035 BKN080 OVC150
Cloud layers reported as coverage and height. Coverage codes:
- SKC / CLR: clear skies, no clouds below 12,000 ft
- FEW: 1-2 oktas (1/8 to 2/8 sky covered)
- SCT: scattered, 3-4 oktas
- BKN: broken, 5-7 oktas. This counts as a ceiling.
- OVC: overcast, 8 oktas. Full cloud cover. This is a ceiling.
Heights are in hundreds of feet AGL. BKN080 means broken ceiling at 8,000 ft AGL. OVC150 means overcast at 15,000 ft AGL. The ceiling is the lowest broken or overcast layer, in this example 8,000 ft.
CAVOK (Ceiling and Visibility OK) is used outside the US and means visibility 10 km or greater, no clouds below 5,000 ft, no cumulonimbus, no significant weather.
Temperature and dew point: 14/02
Temperature / dew point in Celsius. 14°C = 57°F. Dew point 02°C = 36°F. The spread between temperature and dew point matters: a spread of 3°C or less means fog is likely. In this example, the 12°C spread means fog risk is low.
Negative values are prefixed with M. M03/M08 means -3°C temperature, -8°C dew point.
Altimeter: A2987
Barometric pressure in inches of mercury. A rapidly falling altimeter reading indicates an approaching low-pressure system and deteriorating weather.
Weather Phenomena You Will Encounter
METARs can include present weather codes between the visibility and sky condition fields. Common ones for drone pilots:
- -RA: light rain. RA: moderate rain. +RA: heavy rain.
- -SN: light snow. Consumer drones are generally not waterproof.
- FG: fog (visibility below 5/8 SM). BR: mist (visibility 5/8 to 6 SM).
- TS: thunderstorm. Do not fly. Do not be near the aircraft.
- FZ prefix: freezing. FZRA = freezing rain. Ice accumulation on props is a structural emergency.
- BLDU / BLSA: blowing dust / blowing sand. Damages motors and sensors.
How Far Away Is the METAR Station?
METARs are point observations at the airport. Conditions 10 miles away can differ significantly, particularly for wind and visibility. Use the METAR as a baseline, especially for ceiling and wind trends, but always assess conditions at your actual flight location before launching.
UAS SkyCheck shows you the METAR from the nearest airport alongside the distance to that station, so you know how relevant the observation is to your actual location.
UAS SkyCheck shows the raw METAR alongside parsed ceiling, visibility, and wind (plus the distance to the reporting station) in every check. Try it free at uas-skycheck.app, no account required.