Part 107 ACS Task Area 3: Weather
Quick answer
What weather knowledge does the Part 107 test require?
Task Area 3 tests reading a METAR (current conditions report) and a TAF (forecast report), knowing where to find them, and understanding how wind, temperature, density altitude, and icing affect a small drone's performance. You are not tested on forecasting, only on reading official reports and applying them to a go or no-go decision.
Weather is Task Area 3 of the Unmanned Aircraft General, Small (UAG) Airman Certification Standards (ACS), and it is the task area most candidates cite as the second hardest after airspace, largely because it introduces two coded report formats, METAR and TAF, that look unreadable the first time you see them. Both are pulled directly from manned-aviation weather reporting, adapted with no changes for Part 107 purposes, so the coding itself is not drone-specific; you are learning a standard aviation-weather literacy skill.
METAR: current conditions
A METAR (Meteorological Aerodrome Report) is a routine, coded report of current weather
conditions at an airport, typically issued once an hour. A METAR reads left to right in a fixed
order: station identifier, time (in Coordinated Universal Time, UTC, called “Zulu” time in
aviation), wind direction and speed, visibility, present weather, sky condition (cloud layers and
ceiling), temperature and dew point, and altimeter setting. For example, 22015G25KT means wind
from 220 degrees at 15 knots, gusting to 25 knots. Learning the format is mostly learning to
parse the fixed field order and a short set of abbreviations (SCT for scattered clouds, OVC
for overcast, BKN for broken).
TAF: the forecast
A TAF (Terminal Aerodrome Forecast) uses the same coding conventions as a METAR but forecasts
conditions at an airport for a set future window, typically 24 to 30 hours, issued four times a
day. Where a METAR is a snapshot, a TAF is a forecast broken into time periods, each introduced
by a change indicator (FM for “from,” BECMG for “becoming,” TEMPO for “temporary”) showing
when conditions are expected to shift. The knowledge test expects you to read a TAF and identify
what conditions are forecast for a specific time within its window, not to write one yourself.
Where to get official weather
The FAA-recognized source for aviation weather, including current METARs and TAFs, is the Aviation Weather Center (aviationweather.gov), operated by the National Weather Service. A 1-800-WX-BRIEF phone briefing and Automatic Terminal Information Service (ATIS) broadcasts at towered airports are other standard sources referenced in study materials, though for most Part 107 pilots the Aviation Weather Center’s website or an equivalent app is the practical daily tool.
Weather effects on small UAS performance
Beyond reading reports, this task area tests understanding how weather actually changes how a small drone flies:
- Wind affects control authority and battery consumption disproportionately for small, lightweight aircraft compared to manned aircraft; a wind speed that is a non-issue for a Cessna can be a real limit for a small multirotor.
- Density altitude, the pressure altitude corrected for non-standard temperature, increases with heat and elevation and reduces propeller and motor efficiency, cutting into lift and climb performance exactly when a pilot might assume “it’s a calm, sunny day, performance should be fine.”
- Structural icing can add weight and disrupt airflow over rotors or wings, and small UAS generally have no de-icing capability, making icing conditions a hard no-fly rather than a manageable risk.
- Temperature extremes affect battery performance and endurance directly; cold weather in particular reduces usable flight time, a practical fact test questions sometimes frame as a performance-planning scenario.
How this gets tested
Expect a mix of “decode this METAR or TAF field” questions and scenario questions that give you a weather report and ask whether conditions support a safe flight, or how a specific condition (gusting wind, a forecasted temperature drop, a marginal ceiling) would affect the flight. You are never asked to forecast weather yourself, only to read an official report accurately and reason about its operational effect. Because this task area rewards repeated exposure to the report formats more than memorized rules, work through METAR and TAF questions in the free practice bank until the field order stops feeling like a foreign language.