How to Read a METAR

What Is a METAR?#

A METAR (Meteorological Aerodrome Report) is a standardized aviation weather observation issued at airports worldwide, reporting current surface conditions critical for flight operations. This guide is part of Aviatopia's Aviation Weather Explained series.

It is a structured, coded report issued at regular intervals — typically every hour — and used by pilots, dispatchers, air traffic control, and airline operations teams to assess real-time conditions at a specific aerodrome.

Unlike a forecast such as a TAF, a METAR reports observed weather at the time of issuance.

Why It Matters in Aviation#

Weather directly affects aircraft performance, runway selection, fuel planning, approach minima, alternate requirements, and safety margins.

A single METAR can determine:

• Whether a flight may depart under VFR or must operate IFR
• Which runway is favored based on wind direction
• Whether visibility meets instrument approach minimums
• If icing conditions may exist in the departure or arrival phase
• How pressure and temperature affect density altitude (see Density Altitude Explained)

Accurate interpretation is foundational to safe flight operations.

How It Works#

A METAR follows a fixed sequence of coded groups. Each section conveys specific operational data in a globally standardized format.

Example:

METAR KJFK 151651Z 18012G20KT 150V220 10SM R04/2400FT -RA FEW025 SCT080 BKN200 22/16 A2992 RMK AO2

Let’s decode it step by step.

1. Station Identifier#

KJFK

The four-letter ICAO airport code.

• “K” = United States
• “JFK” = John F. Kennedy International Airport

2. Date and Time#

151651Z

• 15 = Day of month
• 1651 = 16:51 UTC
• Z = Zulu time (UTC)

All METAR times are reported in UTC.

3. Wind#

18012G20KT

• 180 = Wind direction (true degrees)
• 12KT = 12 knots
• G20 = Gusting to 20 knots

Wind direction is reported in true degrees, not magnetic.

If wind direction varies significantly:

150V220

This indicates wind direction varying between 150° and 220°.

If wind is light and variable:

VRB03KT

4. Visibility#

10SM

• 10 statute miles visibility

In many countries, visibility is reported in meters instead of miles.

Reduced visibility example:

4000

Indicates 4,000 meters visibility.

Visibility affects approach minima and VFR legality.

5. Runway Visual Range (RVR)#

R04/2400FT

This reports Runway Visual Range for Runway 04.

• 2400FT = Pilot can see 2,400 feet down the runway

RVR becomes critical during low-visibility operations and instrument approaches.

6. Weather Phenomena#

If present, appears after visibility or RVR.

Examples:

• RA = Rain
• TS = Thunderstorm
• BR = Mist
• FG = Fog
• SN = Snow

Intensity modifiers:

• -RA = Light rain
• +TSRA = Heavy thunderstorm rain

7. Cloud Coverage#

FEW025 SCT080 BKN200

Cloud layers are reported in hundreds of feet above ground level (AGL).

• FEW025 = Few clouds at 2,500 ft AGL
• SCT080 = Scattered clouds at 8,000 ft AGL
• BKN200 = Broken clouds at 20,000 ft AGL

Cloud coverage definitions:

• FEW = 1–2 oktas
• SCT = 3–4 oktas
• BKN = 5–7 oktas
• OVC = 8 oktas (overcast)

The ceiling is defined as the lowest BKN or OVC layer.

If the sky is obscured:

VV002

This indicates vertical visibility of 200 ft AGL due to obscuration (fog, heavy precipitation).

8. Temperature and Dew Point#

22/16

• 22°C air temperature
• 16°C dew point

A small temperature–dew point spread indicates high humidity and potential fog formation.

Temperature and pressure together influence aircraft performance (see How Jet Engines Work).

9. Altimeter Setting#

A2992

• Altimeter setting = 29.92 inches of mercury

Outside the United States, pressure is typically reported in hectopascals:

Q1013

Correct altimeter settings ensure accurate altitude indication and terrain separation (see How Airplanes Fly).

10. Remarks (RMK)#

RMK AO2

Additional automated or manual observations.

AO2 indicates automated station with precipitation sensor.

Remarks may include:

• Sea-level pressure
• Exact temperature to tenths of a degree
• Lightning information
• Pressure tendency

METAR vs TAF#

A METAR reports observed weather conditions.

A TAF (Terminal Aerodrome Forecast) provides forecast conditions for a specified future period.

Pilots use both together: METAR for current conditions and TAF for planning.

Operational Example#

A pilot preparing for departure receives:

METAR VOBL 150600Z 27018G28KT 4000 TSRA BKN015 24/23 Q1004

Operational interpretation:

• Strong westerly winds with gusts
• Reduced visibility (4 km)
• Thunderstorm with rain
• Broken ceiling at 1,500 ft AGL

This implies:

• Crosswind considerations depending on runway orientation
• Possible wind shear or microburst activity
• Instrument departure required
• Performance penalties due to high humidity and low pressure

Weather directly shapes operational decisions.

Step-by-Step Breakdown#

Common Misconceptions#

“Wind direction is magnetic.” METAR wind is reported in true degrees.

“Scattered clouds create a ceiling.” Ceiling is only BKN, OVC, or VV.

“10SM always means unlimited visibility.” It means visibility is 10 statute miles or greater.

“Vertical visibility is cloud height.” It indicates obscured sky with an estimated vertical limit.

Frequently Asked Questions#

Key Takeaways#

• A METAR is a real-time aerodrome weather observation.
• Wind is reported in true degrees and may include gusts or variability.
• Visibility may be in statute miles or meters; RVR supplements low-visibility operations.
• Ceiling is the lowest BKN, OVC, or VV layer reported in feet AGL.
• Temperature and dew point influence fog formation and aircraft performance.
• Altimeter settings ensure accurate altitude indication.
• Accurate METAR interpretation is essential for safe flight operations and regulatory compliance.

Sources & References#

• FAA Advisory Circular AC 00-45 — Aviation Weather Services — Official guidance on interpreting METARs, TAFs, and other weather products.
• FAA Aeronautical Information Manual (AIM), Chapter 7 — Safety of flight information, including weather services and reports.
• ICAO Annex 3 — Meteorological Service for International Air Navigation — International standards for METAR format and dissemination.

Related Guides#

• How to Read a TAF
• Runway Visual Range (RVR)
• Airport Operations 101

Browse Directories#

• METAR & TAF Codes — Full reference of sky condition, visibility, wind, and weather-phenomena codes.

More in Aviation Weather#

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