How can you interpret a METAR report?

1 What is METAR?

METAR stands for Meteorological Terminal Air Report, and it is a coded message that contains information about the current weather at a specific airport. METAR reports are issued every hour or half-hour, or more frequently if there are significant changes in the weather. METAR reports are usually transmitted by radio or displayed on aviation websites and apps.

2 How is METAR structured?

A METAR report consists of several sections, each separated by a space. The station identifier is a four-letter code that indicates the location of the airport, such as KJFK for John F. Kennedy International Airport in New York or EGLL for London Heathrow Airport. The date and time is a six-digit group that shows the day of the month and the time of the observation in UTC (Coordinated Universal Time). For example, 251230Z means the 25th day of the month at 12:30 UTC. The wind is a five-digit group that shows the direction and speed of the wind in degrees and knots. For example, 27015KT means the wind is blowing from 270 degrees (west) at 15 knots. If the wind is variable, the group may include the range of directions. The visibility is a two- or four-digit group that shows the horizontal visibility in statute miles. If visibility is less than one mile, it may include fractions. The weather includes one or more groups that show the type and intensity of weather phenomena, such as rain, snow, fog, thunderstorms, etc., using abbreviations and symbols. The sky condition includes one or more groups that show the amount and type of clouds in the sky, as well as the ceiling (the lowest layer of clouds that covers more than half of the sky). It uses abbreviations and numbers to indicate cloud coverage and height. The temperature and dew point is a two-digit group that shows air temperature and dew point temperature in degrees Celsius, separated by a slash. The dew point temperature indicates humidity and possibility of fog or frost. Lastly, the altimeter setting is a four-digit group that shows atmospheric pressure at airport in inches of mercury, preceded by letter A. This setting is used to adjust altimeter in aircraft to show correct altitude above sea level.

3 How to decode a METAR report?

To decode a METAR report, you need to identify and understand each section of the report, and use a reference table or a decoder tool to translate the abbreviations and symbols. For example, let's consider this METAR report for John F. Kennedy International Airport (KJFK): KJFK 251230Z 27015G25KT 240V300 10SM -RA SCT020 BKN040 OVC080 18/12 A2992. This means that the report was issued on the 25th day of the month at 12:30 UTC (251230Z), with the wind blowing from 270 degrees (west) at 15 knots, gusting to 25 knots, and varying between 240 and 300 degrees (27015G25KT 240V300). The visibility is 10 statute miles (10SM), with light rain (-RA), scattered clouds at 2,000 feet, broken clouds at 4,000 feet, and overcast clouds at 8,000 feet (SCT020 BKN040 OVC080). Additionally, the air temperature is 18 degrees Celsius and the dew point temperature is 12 degrees Celsius (18/12), with an altimeter setting of 29.92 inches of mercury (A2992).

4 How to interpret a METAR report?

Interpreting a METAR report requires knowledge and judgment to assess the weather conditions and their potential impacts on your flight. For example, based on the METAR report for KJFK, you can gather that the wind is strong and variable, potentially causing turbulence and crosswind during takeoff and landing. The visibility is good, so you can see the runway and other traffic easily. The rain is light, which may not affect visibility much but may reduce the braking action on the runway. The clouds are low and thick, which could reduce the ceiling and require you to fly under IFR or VFR with special clearance. The temperature and dew point are close, indicating there is a chance of fog or frost forming. Lastly, the pressure is high, suggesting that the weather is stable and not likely to change rapidly.

5 How to practice reading and interpreting METAR reports?

Practicing reading and interpreting METAR reports is key to improving your weather awareness and decision making skills as a pilot. Resources like the Aviation Weather Center, METAR Decoder, and METAR Quiz can help you do this. By regularly reading and interpreting METAR reports, you can compare your interpretation with actual weather conditions and learn from any mistakes or gaps in your knowledge. However, it's important to remember that METAR reports are only one source of weather information, so you should always check other sources like TAFs, weather radar, and PIREPs before and during your flight.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?