METAR vs TAF: How to Read Weather Briefings for Part 107 Drone Flights

METARs report current weather conditions and TAFs forecast them, and both are essential for legal Part 107 drone flights. Before every flight, §107.49(a)(1) requires you to assess local weather conditions, and §107.51 forbids operations with less than 3 statute miles of flight visibility or closer than 500 feet below and 2,000 feet horizontally from clouds. METARs tell you whether conditions are legal right now; TAFs tell you whether they will stay legal for your planned flight.

Why Weather Reports Matter for Part 107

The visibility and cloud rules in §107.51 are hard limits, not suggestions. A METAR's visibility group tells you whether you have the required 3 statute miles, and its sky condition group shows where the clouds are so you can respect the 500-foot and 2,000-foot clearances. Weather is also a tested knowledge area on the UAG exam (§107.73(c)).

How to Read a METAR

Here is a routine METAR from Chicago O'Hare:

KORD 241752Z 24012KT 10SM SCT025 30/22 A2990

Station and Time

KORD identifies the airport, and 241752Z means the report was taken on the 24th of the month at 17:52 UTC (Zulu time).

The Wind Group

24012KT means the wind is from 240 degrees true at 12 knots. Gusts appear as 24015G25KT: 15 knots sustained with gusts to 25. VRB means variable direction, and 00000KT means calm.

Visibility

10SM means 10 statute miles of prevailing visibility. Fractional values such as 1/2SM and 2 1/2SM are common. Compare this group directly against the 3-statute-mile minimum in §107.51.

Sky Condition

SCT025 means scattered clouds at 2,500 feet above ground level. Coverage codes are FEW (1-2 octas), SCT (3-4), BKN (5-7), and OVC (8). Heights are in hundreds of feet, so BKN040 is broken at 4,000 feet. A ceiling exists when the layer is BKN, OVC, or reported as vertical visibility (VV).

Temperature, Dew Point, and Altimeter

30/22 means 30°C with a dew point of 22°C; an M prefix marks below-zero values. A2990 is the altimeter setting, 29.90 inches of mercury. Temperature and dew point affect battery performance and moisture risk, which is why the effects of weather on performance are a tested subject.

METAR vs TAF: The Difference

• METAR: observed conditions, issued hourly, with SPECI reports between hours when conditions change significantly.
• TAF: forecast conditions, issued every 6 hours, valid for 24 hours at most airports and 30 hours at some major ones.
• TAFs use METAR codes plus change groups: FM (from), TEMPO (temporary), BECMG (becoming), and PROB30 or PROB40 (probability).

How to Read a TAF

A TAF opens with a validity line such as 2418/2524, meaning the forecast runs from the 24th at 18Z through the 25th at 24Z. Change groups mark expected shifts: TEMPO 0608/0611 2SM -SHRA means visibility could drop to 2 statute miles with light rain showers from 06Z to 11Z, conditions that would make your flight illegal under §107.51. Amended forecasts are marked TAF AMD.

Use Both Reports in Your Preflight

Check the METAR at your launch site first: is visibility at least 3 statute miles, and are clouds high enough for the required clearances? Then read the TAF: will conditions hold for the whole flight, or will a TEMPO group push visibility below legal limits? Wind groups also feed into loading and performance checks, since strong winds affect control authority and battery endurance. Free sources such as the National Weather Service aviation weather page provide both reports.

Next Steps

Weather is one of the eight theory chapters on sky107.com, with animated diagrams that make decoding METARs and TAFs intuitive. Test yourself with free practice questions, follow the study checklist, and complete the picture with our certification guide, Remote ID explainer, and sectional chart guide.