How to read a METAR and a TAF for the Part 107 test

A METAR reports what is happening now

A METAR is an observation of conditions at an airport at a stated time. The groups always appear in the same order: station, date and time, wind, visibility, weather, sky condition, temperature and dewpoint, and altimeter setting, followed by any remarks.

Times are in Coordinated Universal Time, marked Z (Zulu). 241753Z means the 24th of the month at 17:53 UTC. Reading it as local time is a common mistake.

Decoding the groups

Take METAR KXYZ 241753Z 27012G20KT 10SM -RA BKN025 OVC040 18/12 A2992:

• 27012G20KT: wind from 270 degrees true at 12 knots, gusting to 20.
• 10SM: visibility 10 statute miles.
• -RA: light rain. A plus sign means heavy; no sign means moderate.
• BKN025 OVC040: broken clouds at 2,500 feet AGL, overcast at 4,000 feet AGL. Cloud heights are in hundreds of feet above ground level.
• 18/12: temperature 18°C, dewpoint 12°C. An M in front means minus.
• A2992: altimeter setting 29.92 inches of mercury.

Sky cover and the ceiling

FEW means 1 to 2 eighths of the sky covered, SCT (scattered) 3 to 4 eighths, BKN (broken) 5 to 7 eighths and OVC (overcast) the whole sky. The ceiling is the lowest broken or overcast layer, or a vertical visibility (VV) into an obscuration. FEW and SCT layers are never the ceiling. In the example above the ceiling is 2,500 feet AGL.

A TAF forecasts what is expected

A TAF is a forecast for the area within 5 statute miles of an airport, usually covering 24 or 30 hours. It uses the same groups as a METAR, plus change groups that say when conditions will shift.

• 2418/2518: the valid period, from the 24th at 18Z to the 25th at 18Z.
• FM242200: from 22:00 UTC on the 24th, a lasting change to the conditions that follow.
• TEMPO 2500/2504: temporary fluctuations during that window, each lasting less than an hour.
• PROB30: a 30 percent probability of the conditions that follow.