How to Read a METAR – A Comprehensive Guide

What Is a METAR Report?

A METAR report—an acronym for Meteorological Terminal Air Report (or Meteorological Aerodrome Report)—is a standardized format for transmitting current weather observations.

These reports provide essential data for flight planning and safety.

Reading and interpreting these reports is a fundamental skill for any aviator.

Key Components of a METAR Report

At first glance, a METAR report can look like an indecipherable line of code.

A standard report contains several components in a specific order:

• Type of Report

• Station Identifier: The four-letter ICAO code for the airport.

• Date and Time: The observation time in UTC (Zulu time).

• Modifier: Indicates if the report is automated (e.g., AUTO).

• Wind: Direction and speed, including gusts.

• Visibility: Prevailing surface visibility.

• Weather Phenomena: Significant weather like rain (RA) or haze (HZ).

• Sky Condition: Cloud cover and height.

• Temperature and Dew Point: Reported in Celsius.

• Altimeter Setting: Barometric pressure.

• Remarks: An optional section for additional information.

Understanding Wind Information in METAR

Immediately following the station identifier and time, you’ll find the wind information.

Accounting for sudden changes in wind speed, known as gusts, is critical for aviation safety.

Wind direction isn’t always constant.

Interpreting Cloud Cover and Sky Conditions

After wind and visibility, the METAR report details the sky conditions, giving pilots a clear picture of what’s above.

The key abbreviations for cloud cover are:

• SKC: Sky Clear

• FEW: Few clouds (1-2 OKTA)

• SCT: Scattered clouds (3-4 OKTA)

• BKN: Broken layer (5-7 OKTA)

• PVC: Overcast (8 OKTA)

Each code is followed by a three-digit number representing the cloud base height in hundreds of feet above ground level (AGL).

Certain cloud types require special attention due to their association with hazardous weather.

How to Read a METAR Report

Decoding a METAR report is a systematic process, much like reading a sentence from left to right.

METAR Examples with Detailed Analysis

The best way to become proficient at decoding Meters is through practice.

Example 1: Boston Logan International Airport (KBS)

METAR: KBS 081730Z AUTO 18008KT 3SM HZ SHVC BKN020 20/16 A2993

• KBS: The ICAO station identifier for Boston Logan International Airport.

• 081730Z: The observation was taken on the 8th day of the month at 17:30 Zulu (UTC) time.

• AUTO: The report was generated by an automated weather station.

• 18008KT: Wind is from 180 degrees (a true south wind) at 8 knots.

• 3SM: Flight visibility is 3 statute miles.

• HZ: Haze is present in the atmosphere.

• SVC: There are showers in the vicinity of the airport.

• BKN020: The sky has a broken cloud layer at 2,000 feet above ground level (AGL).

• 20/16: The temperature is 20°C, and the dew point is 16°C.

• A2993: The altimeter setting is 29.93 inches of mercury.

This report tells a pilot that conditions at Boston are somewhat marginal, with reduced visibility due to haze and a relatively low cloud ceiling.

Example 2: Denver International Airport (KEEN)

METAR: KEEN 152253Z 33015G25KT 1SM -SN OVC010 M02/M04 A3012

• KEEN: The ICAO station identifier for Denver International Airport.

• 152253Z: The observation was taken on the 15th day of the month at 22:53 UTC.

• 33015G25KT: Wind is from 330 degrees at 15 knots, with gusts (G) up to 25 knots.

• 1SM: Visibility is restricted to 1 statute mile.

• -SN: Light snow is falling (the minus sign indicates ‘light’).

• OVC010: The sky is overcast with a ceiling at 1,000 feet AGL.

• M02/M04: The temperature is minus 2°C, and the dew point is minus 4°C (the ‘M’ stands for ‘minus’).

• A3012: The altimeter setting is 30.12 inches of mercury.

A pilot reading this would immediately recognize challenging flight conditions due to the strong gusts, low visibility, and snow.

Differences Between METAR and TAF Reports

While both are essential aviation weather reports, METAR and TAF (Terminal Aerodrome Forecast) have distinct purposes based on their time reference:

| Feature | METAR (Observation) | TAF (Forecast) |

|—|—|—|

| Purpose | Describes current weather conditions | Predicts future weather conditions |

| Timeframe | A snapshot of the present moment | Covers a 24- to 30-hour period |

| Update Cycle | Hourly (or more often if weather changes) | Typically every 6 hours |

| Focus | Detailed, comprehensive look at all conditions | Highlights significant expected weather changes |

When to Use METAR Reports

A METAR report is the definitive source for pilots and aviation personnel needing an accurate picture of current weather conditions on the ground.

Pilots use these reports for several critical tasks:

• Pre-flight Planning: To confirm that conditions like wind, visibility, and cloud ceilings are within safe operational limits.

• Takeoff Calculations: To use precise wind data for selecting the correct runway and calculating takeoff performance.

• In-flight Adjustments: To monitor conditions at the destination and alternate airports, enabling timely diversions if weather deteriorates.

METAR reports are also valuable in other aviation sectors.