How to Read METAR Weather Report?

Step-by-Step METAR Decoding Guide

Trying to decode an entire METAR string at once can be overwhelming. A better approach? Break it down into smaller chunks—each delivering a specific type of weather data. That’s how METARs are designed: concise, structured, and packed with vital information.

Let’s walk through a real-world METAR, breaking it down into 10 core components.

Standard METAR Sequence:

1. Report Type

The report always begins with either METAR or SPECI:

• METAR: Routine weather observation, issued hourly.
• SPECI: Special, unscheduled report due to rapidly changing or hazardous conditions (e.g., thunderstorms, fog, or snow).

Knowing the type immediately tells pilots whether conditions are stable or quickly evolving.

2. Airport Identifier

After the report type, you'll see a four-letter ICAO code that identifies the airport or weather station. Unlike the three-letter IATA codes used for ticketing, ICAO codes are regionally structured and used in flight planning and operations worldwide.

• Continental U.S.: Start with “K” plus the IATA code (e.g., KSEA = Seattle).
• Alaska, Hawaii, Guam, Puerto Rico: Begin with “P” (e.g., PA for Alaska, PH for Hawaii, PG for Guam, TJ for Puerto Rico).
• Canada: Prefixes like CY, CZ, CU, or CW.
• Mexico: Typically MM (e.g., MMMX = Mexico City).

This code ensures that weather data is tied to the correct location—critical in metro areas with multiple airports, such as KAPA (Centennial Airport, Colorado) or VHHH (Hong Kong International).

3. Date and Time

Next comes the date and time of issue. The first two digits (20) correspond to the day of the month, and the last four digits (2124) correspond to the time of issue in hours and minutes.

The "Z" appended to the end signifies Coordinated Universal Time (UTC), also known as Zulu time or Greenwich Mean Time (GMT).

In our example, the METAR was issued on the 20th of the month at 21:24 Zulu time. Pilots are responsible for converting this to their local time.

The timeliness of a METAR is paramount, as reports are generally valid for only one hour.

4. Modifier

This optional element provides context about the report's origin or if it's a correction.

• AUTO indicates a fully automated report generated without human intervention or oversight. Automated stations may further detail their sensor types in the remarks section (e.g., AO1 for no precipitation discriminator, AO2 for a precipitation discriminator). 
• COR identifies a corrected report that replaces an earlier one containing an error.
• If no modifier is present, it implies a human observer directly created the report or was actively overseeing the automated system.

Modifiers help assess data reliability. Automated reports can miss subtle or fast-changing conditions, while human observers provide greater accuracy in complex weather like moving fog or storms.

5. Wind

Wind data is presented as a three-digit direction, followed by a two- or three-digit speed, and then "KT" for knots.

• Direction indicates where the wind is coming from, measured in tens of degrees from true north (e.g., 160 means from 160 degrees). Leading zeros are used for directions less than 100° (e.g., 090 for 90°).
• Speed is in knots (KT). Speeds less than 10 KT use a leading zero (e.g., 05KT).
• Gusts are shown with "G" and peak gust speed (e.g., 16005G17KT = 5 knots gusting to 17). Indicates rapid wind variation. 
• Variable Wind (VRB) is used if the wind direction is fluctuating significantly (e.g., by 60° or more, or if speed is 3 knots or less, or if direction cannot be determined).
• Calm Wind is reported as 00000KT.

For example, 16005KT indicates wind from 160 degrees at 5 knots. 24015G25KT means wind from 240 degrees at 15 knots, gusting to 25 knots.

Wind information is crucial for runway selection (ideally landing into a headwind), calculating crosswind components, and avoiding dangerous tailwinds.  

6. Visibility

This section describes the horizontal visibility at the airport.

In the U.S., prevailing visibility is reported in statute miles (SM), in whole numbers or fractions. An "M" prefix means "less than" (e.g., M1/4SM for less than 1/4 statute mile). The maximum visibility listed is 10 SM, even if it's greater.

Internationally, visibility is often reported in meters (e.g., 0600 for 600 m). 9999 indicates 10 km or more, while 0000 signifies less than 50 m.

At larger airports, especially during low visibility conditions (typically when prevailing visibility is 1 mile or 1600 m or less), Runway Visual Range (RVR) may be reported. This is formatted as R followed by the runway designator (e.g., R07L), then a slash (/) and a four-digit value in feet (U.S.) or meters (international).

A letter may follow the value to indicate tendency: U (upward/increasing), D (downward/decreasing), N (no significant change), or V (variable).

7. Weather

This section utilizes two-letter codes, often preceded by indicators of intensity or descriptors, to describe current weather phenomena. These descriptors add further detailed information, designed to present a fuller picture.

Here is a list of common elements that could be reported: