What is a METAR and why do Part 107 drone pilots need to read one?

A METAR (Aviation Routine Weather Report) is a standardized surface weather observation issued at regular intervals, typically every hour, that reports current conditions at an airport including wind speed and direction, visibility, sky condition, temperature, dewpoint, and altimeter setting. Part 107 remote pilots must assess these factors before flight because FAA regulations require operations only in conditions safe for the drone and the National Airspace System. While METARs are generated at airports, they provide the best available official surface weather data near a proposed flight area. The FAA Pilot's Handbook of Aeronautical Knowledge (PHAK) identifies METARs as a primary aviation weather product.

How do you decode the visibility and cloud cover fields in a METAR for a drone flight?

Visibility in a METAR is reported in statute miles as a whole number or fraction, for example '10' means 10 statute miles and '1/2' means half a statute mile, which is critical because Part 107 requires the remote pilot to maintain visual line of sight with the drone. Sky condition is reported using contractions such as FEW (1–2 oktas), SCT (scattered, 3–4 oktas), BKN (broken, 5–7 oktas), or OVC (overcast, 8 oktas), followed by the cloud base height in hundreds of feet AGL. For Part 107 operations, broken or overcast layers create a ceiling that can restrict how high a drone may safely operate and still remain clear of clouds, since regulations require specific cloud clearance distances. Reviewing these fields helps a remote pilot determine whether visual meteorological conditions exist at the proposed operating area.

What's the difference between a METAR and a SPECI, and does it matter for Part 107 operations?

A METAR is a routine hourly surface weather observation, while a SPECI is a special, unscheduled observation issued when significant weather changes occur between routine reports, such as a sudden drop in visibility, wind shift, or the appearance of thunderstorms. For Part 107 remote pilots, SPECIs are important because conditions can deteriorate rapidly, and relying only on an hourly METAR could mean missing a hazardous change that occurred minutes earlier. The Aviation Weather Handbook (FAA-H-8083-28) highlights that pilots should check for SPECIs when weather is variable or potentially convective. Monitoring both report types before and during a drone operation supports the Part 107 requirement to maintain safe operating conditions throughout the flight.

Aviation Routine Weather Report (METAR) Decoding for Part 107

The Aviation Routine Weather Report, universally known by its French acronym METAR, is the most widely available and standardized surface weather observation in aviation. For Part 107 remote pilots, the METAR is not just a regulatory checkbox — it is the single most actionable piece of weather data available before and during a drone flight. Understanding how to decode every field quickly and accurately can mean the difference between a safe, legal operation and a violation or crash.

METARs are issued by weather observation stations — typically at airports — either once per hour (routine) or as a special observation called a SPECI when significant weather changes occur. While drone pilots may not always operate at or near an airport, finding the nearest reporting station and understanding how local terrain and distance affect conditions is a core skill. The FAA's Aviation Weather Handbook (FAA-H-8083-28) establishes METARs as the foundation of surface weather assessment for all pilots, including remote pilots operating under 14 CFR Part 107.

The Standard METAR Format — Field by Field

A METAR is always presented in a fixed sequence of coded groups. Once you learn the order, decoding becomes fast and reliable. Here is a representative example broken into its components:

METAR KDFW 211753Z 18012KT 10SM FEW030 SCT080 BKN250 28/18 A2995 RMK AO2 SLP142 T02830183

Type and Station Identifier

The report begins with the word METAR (routine) or SPECI (special). The four-letter ICAO station identifier follows — U.S. airports begin with the letter K (e.g., KDFW = Dallas/Fort Worth). Smaller stations may use three-letter identifiers preceded by K. Knowing your nearest reporting station is essential for Part 107 pre-flight planning.

Date and Time (DTG)

The date-time group 211753Z means the 21st day of the month, at 1753 Zulu (UTC). All METARs use UTC — not local time. Part 107 pilots must convert to local time as needed but should always log and reference times in UTC when filing waivers or incident reports. Confusing UTC with local time is a common and dangerous mistake.

Wind

The wind group 18012KT decodes as: wind from 180° (due south) at 12 knots. The three-digit direction is reported in degrees true (referenced to true north), not magnetic — METAR wind directions are only converted to magnetic for ATIS and tower broadcasts. If gusts are present you will see a format like 18012G22KT, meaning gusts to 22 knots. Variable winds below 6 knots are shown as VRB03KT. When winds exceed the 10–12 knot range, small multirotor drones begin to experience significant handling issues, and remote pilots should cross-reference manufacturer wind limits before flight.

A wind direction range is sometimes appended — for example 160V220 — indicating the wind is variable between 160° and 220°. This is particularly significant for drone operations because variable winds create unpredictable attitude disturbances.

Visibility

Prevailing visibility 10SM means 10 statute miles. Part 107 requires that the remote pilot maintain visual line of sight (VLOS) with the drone. While Part 107 does not impose a specific minimum flight visibility the way manned aviation does, the regulation requires the remote pilot, visual observer, or both to be able to see the aircraft clearly enough to determine its attitude, altitude, and direction at all times. In practice, if visibility drops below 3 statute miles, maintaining VLOS becomes extremely challenging, and below 1 mile it is essentially impossible for any normal operation. Reduced visibility from haze, smoke, fog, or precipitation is one of the top causes of VLOS loss for drone pilots.

Fractional visibilities such as 1/2SM or 1 1/4SM indicate very low visibility conditions. A M prefix (e.g., M1/4SM) means less than that value.

Present Weather

Weather phenomena appear between visibility and sky condition using two-letter descriptor codes. Common examples include: RA (rain), SN (snow), FG (fog), BR (mist/light fog, visibility 5/8 to 6 SM), TS (thunderstorm), DZ (drizzle), SQ (squall), and HZ (haze). Intensity modifiers precede the code: a minus sign (−) means light, no modifier means moderate, and a plus sign (+) means heavy. Thunderstorms (+TSRA) represent an absolute no-fly condition for Part 107 operations due to extreme turbulence, lightning, and rapid visibility changes.

Sky Condition

Sky condition is reported in layers, lowest first. Each layer has a coverage descriptor and a height in hundreds of feet AGL: FEW030 = few clouds at 3,000 feet AGL; SCT080 = scattered at 8,000 feet AGL; BKN250 = broken at 25,000 feet AGL. The coverage codes are:

SKC / CLR — Sky clear (no clouds)
FEW — 1–2 oktas (eighths) of sky covered
SCT (Scattered) — 3–4 oktas
BKN (Broken) — 5–7 oktas; constitutes a ceiling
OVC (Overcast) — 8 oktas; constitutes a ceiling
VV (Vertical Visibility) — used when sky is obscured; the number after VV is the vertical visibility in hundreds of feet

For Part 107, this is critical because 14 CFR 107.51 prohibits flight in Class G airspace above 400 feet AGL, and in controlled airspace without authorization. More relevantly, Part 107 operations must remain clear of clouds. The regulation specifies that the remote pilot must not fly in a manner that creates a hazard — flying into or near clouds violates both this rule and the spirit of VLOS requirements. A ceiling at or below the intended altitude is an immediate stop-flight condition.

Temperature and Dewpoint

The group 28/18 gives temperature and dewpoint in degrees Celsius. The spread between temperature and dewpoint is important: a spread of 4°C or less indicates high relative humidity and the potential for fog formation, especially at night when temperatures drop toward the dewpoint. Remote pilots should be alert to rapidly closing temperature-dewpoint spreads during evening operations, which can cause VLOS-destroying ground fog with little warning.

Altimeter Setting

A2995 means the altimeter setting is 29.95 inches of mercury. While drone autopilots use barometric altitude, and GPS is more commonly used, understanding the altimeter setting helps remote pilots understand local pressure patterns. Low pressure systems often bring deteriorating weather, and a rapidly falling altimeter setting is a warning sign of approaching fronts.

Remarks (RMK)

The remarks section follows RMK and contains additional coded and plain-language information. AO2 means the station is an automated station equipped with a precipitation discriminator, meaning it can distinguish liquid precipitation (like rain) from frozen or freezing precipitation (like snow or freezing rain); an AO1 designation indicates an automated station without this discriminator capability. SLP gives sea-level pressure in hectopascals. Plain-language remarks may note phenomena such as TORNADO, FUNNEL CLOUD, or LIGHTNING SW — all critical for drone safety awareness.

Why METARs Matter for Part 107

Part 107 remote pilots are required by 14 CFR 107.49 to assess the operating environment prior to flight, including weather conditions. The METAR directly supports this obligation. Unlike a general weather app, the METAR is an official, time-stamped, standardized aviation observation that provides legally defensible evidence of pre-flight due diligence. It is also free and universally accessible through aviationweather.gov, ForeFlight, and other approved sources.

Beyond compliance, METARs protect your equipment. Most consumer and commercial drones have manufacturer-specified wind limits in the 20–28 knot range, humidity limits, and precipitation restrictions. A METAR gives you real wind speeds, visibility, and precipitation data to compare against those limits — not a guess from a general weather website.

Key Numbers and Rules for the Knowledge Test

METARs are issued once per hour; SPECIs are unscheduled and issued when significant changes occur.
All times in METARs are in UTC (Zulu).
Wind direction in a METAR is given in true degrees to the nearest 10°.
Sky coverage: FEW = 1–2 oktas, SCT = 3–4, BKN = 5–7 (ceiling), OVC = 8 (ceiling).
A ceiling is defined as the lowest broken or overcast layer, or vertical visibility into an obscuration.
Visibility is reported in statute miles in U.S. METARs.
The M prefix before a visibility value means the visibility is less than the stated value.
Temperature and dewpoint are in degrees Celsius.
Altimeter setting is in inches of mercury in U.S. reports (preceded by A).

Common Test Traps

Confusing knots with mph: METAR winds are in knots. One knot equals approximately 1.15 mph. A 15-knot wind is about 17 mph — this matters when comparing to drone manufacturer specs listed in mph.
Misreading the ceiling: FEW and SCT layers are not ceilings. Only BKN and OVC (and VV) define the ceiling. A report of SCT030 does not mean the ceiling is 3,000 feet — there may be no ceiling at all if no BKN or OVC layer is present.
Ignoring the remarks section: Important safety information — lightning, tornados, variable ceiling heights — often appears only in remarks. Stopping at the altimeter setting is a common and dangerous shortcut.
Assuming the METAR is current: A METAR is valid for approximately one hour. Weather can change significantly within that window. Always check the issuance time against your planned operation time, and use SPECIs or real-time updates for rapidly changing conditions.
Forgetting station distance: A METAR from an airport 15 miles away may not represent conditions at your flight site, especially in mountainous terrain, near bodies of water, or when localized weather (fog, thermals, sea breeze) is present. METARs should be supplemented with TAFs, PIREPs, and local observation when the station is not co-located with your operation.