liminfoWeather Code Reference
Free reference guide: Weather Code Reference
About Weather Code Reference
The Weather Code Reference is a searchable decoder for meteorological observation and forecast codes used worldwide in aviation and weather reporting. It covers METAR (routine aerodrome weather observations) with detailed breakdowns of wind groups, visibility, runway visual range (RVR), weather phenomena, cloud groups, temperature/dewpoint, QNH pressure, and trend forecasts. Each code element is explained with real-world examples showing how to read and interpret raw weather reports character by character.
Beyond METAR, this reference includes TAF (Terminal Aerodrome Forecast) codes for validity periods, BECMG, TEMPO, PROB, and FM change indicators, as well as SYNOP surface observation codes (FM 12) including present weather codes (ww 00-99), total cloud amount, and low/mid/high cloud type classifications. Aviation-specific sections cover SIGMET and AIRMET formats for significant weather hazards, turbulence intensity codes, and icing severity/type codes. The weather scales section provides Beaufort wind scale, flight category definitions (LIFR/IFR/MVFR/VFR), cloud amount okta conversions, precipitation intensity prefixes, weather descriptors, and the complete weather type abbreviation list.
All content loads and displays in your browser with no server communication required. Pilots, dispatchers, meteorologists, aviation enthusiasts, and weather hobbyists can instantly search for any code element or browse organized categories: METAR, TAF, SYNOP, Aviation Weather, and Weather Scales. The interface supports dark mode and works seamlessly on desktop, tablet, and mobile devices for quick reference during flight planning or weather briefings.
Key Features
- Complete METAR decoding guide: wind, visibility, RVR, weather phenomena, cloud groups, temperature, QNH, and trends
- TAF forecast codes including validity periods, BECMG, TEMPO, PROB, and FM change group explanations
- SYNOP surface observation codes with present weather (ww), total cloud amount (N), and cloud type (CL/CM/CH) tables
- SIGMET and AIRMET format examples for in-flight hazard awareness and flight planning
- Turbulence (0-4+X) and icing intensity/type codes used in pilot reports and weather advisories
- Beaufort wind scale (0-12) with knot equivalents and flight category definitions (LIFR through VFR)
- Complete weather type abbreviation table covering 30+ phenomena from drizzle to tornado
- Weather descriptor prefixes (MI, BC, DR, BL, SH, TS, FZ, PR) and precipitation intensity modifiers
Frequently Asked Questions
How do I read a METAR report?
A METAR report follows a fixed format: station ID, date/time (UTC), wind (direction/speed/gusts in knots), visibility (meters or SM), weather phenomena (intensity+descriptor+type), cloud groups (amount/height/type), temperature/dewpoint, QNH pressure, and trend. For example, "METAR RKSI 101200Z 27015G25KT 9999 FEW040 SCT100 25/15 Q1013 NOSIG" means Incheon airport, 10th at 12:00Z, wind 270 degrees at 15kt gusting 25kt, visibility 10km+, few clouds at 4000ft, scattered at 10000ft, temp 25C, dewpoint 15C, QNH 1013hPa, no significant change expected.
What is the difference between METAR and TAF?
METAR is an actual observation of current weather conditions at an aerodrome, issued hourly (with SPECI for rapid changes). TAF is a forecast of expected weather conditions, typically valid for 24 or 30 hours. TAF uses change indicators like BECMG (gradual permanent change), TEMPO (temporary fluctuations lasting under 1 hour), PROB (probability), and FM (immediate complete change from a specific time).
How do I decode weather phenomena codes?
Weather phenomena codes combine up to three parts: intensity prefix (- light, none moderate, + heavy, VC vicinity), descriptor (TS thunderstorm, SH shower, FZ freezing, etc.), and type (RA rain, SN snow, FG fog, BR mist, etc.). For example, +TSRA means heavy thunderstorm with rain, -SHRA means light rain shower, FZDZ means freezing drizzle, and VCSH means showers in the vicinity of the airport.
What do the cloud amount abbreviations mean?
Cloud amounts are reported in oktas (eighths of sky coverage): SKC/CLR = 0 oktas (clear sky), FEW = 1-2 oktas, SCT = 3-4 oktas (scattered), BKN = 5-7 oktas (broken), OVC = 8 oktas (overcast). The number after the abbreviation is the cloud base height in hundreds of feet. CB (cumulonimbus) and TCU (towering cumulus) may be appended to indicate convective cloud types.
How do flight categories (VFR/IFR) relate to visibility codes?
Flight categories are determined by the lowest ceiling and visibility: VFR requires visibility >5SM and ceiling >3000ft, MVFR is 3-5SM visibility or 1000-2999ft ceiling, IFR is 1-3SM or 500-999ft, and LIFR is below 1SM or below 500ft. These categories determine flight rules and are critical for pilot decision-making. The reference provides these thresholds alongside visibility reporting formats in both meters and statute miles.
What are the SYNOP present weather codes?
SYNOP uses a two-digit code (ww, 00-99) to describe present weather. Key codes include: 61 light continuous rain, 65 heavy continuous rain, 71 light continuous snow, 80 light rain shower, 95 moderate thunderstorm with rain or snow. The codes are grouped by type: 00-19 no significant weather, 20-29 past weather, 30-39 duststorm/sandstorm, 40-49 fog, 50-59 drizzle, 60-69 rain, 70-79 snow, 80-89 showers, 90-99 thunderstorms.
How are SIGMET and AIRMET different?
SIGMET (Significant Meteorological Information) reports hazardous weather phenomena that affect all aircraft, including embedded thunderstorms, severe turbulence, severe icing, volcanic ash, and tropical cyclones. AIRMET (Airmen Meteorological Information) covers weather conditions hazardous primarily to light aircraft and VFR flights, such as moderate turbulence, moderate icing, IFR conditions, and mountain obscuration. Both include location, movement, and expected changes.
Is this reference suitable for flight planning?
Yes. This reference provides the complete code tables needed to decode METAR, TAF, SIGMET, and AIRMET reports during pre-flight weather briefings. It covers all standard ICAO weather codes, wind groups, visibility formats, cloud reporting, and aviation-specific hazard codes. However, always use official meteorological sources for actual flight planning decisions. This tool serves as a quick-reference decoder, not a weather data provider.