Anatomy of a METAR
Station, time, wind, visibility, weather, cloud, temperature/dew point, pressure. EGLL 121250Z 24012KT 9999 FEW035 18/11 Q1014 means Heathrow, 12th at 12:50Z, wind 240° at 12 kt, visibility 10 km or more, few clouds at 3,500 ft, 18°C, dew point 11°C, QNH 1014 hPa.
Cloud and weather groups
FEW, SCT, BKN and OVC give eighths of sky cover; heights are in hundreds of feet above aerodrome level. Intensity prefixes are minus for light, nothing for moderate and plus for heavy: +RA is heavy rain, TSRA a thunderstorm with rain.
TAF change groups
BECMG marks a gradual change, TEMPO a temporary fluctuation under an hour, PROB30/PROB40 a probability. Always check the validity period before planning against a TAF.
Key points
- 9999 means visibility 10 km or more; 0000 means less than 50 m.
- Cloud bases are above aerodrome level, not sea level.
- Small temperature/dew point spread signals likely fog or low cloud.
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