Metar Decoding Made Easy



METAR decoding knowledge is essential because, when you need real time weather observations, METARS are the most easily accessible of all types of real time weather data.

METAR stands for "Meteorological Aviation Report". This type of report is very complete (see table below). METARS are so complete, in fact, that they will likely exceed your requirements for actual weather information, if you are not an aircraft pilot.

METARS are used by both civil and military, for flight planning and in-flight decision making purposes. Pilots also use TAFORS - Terminal Area Forecasts - which are also available in coded, and plain language forms.

You can get real time METAR weather here.

The observations are available in coded form - the METAR code (see below) - and are also presented in decoded "plain language" form.

Symbolic Form Of "METAR" Code

METAR CCCC YYGGggZ AUTO ddffGfmfmKT VVVVDv w'w' NSNSNShshshs or VVhshshs or CLR TT/T'dT'd APHPHPHPH RMK SLPXXX

Example Of A "METAR" Report

Let's practice METAR decoding with an example of a METAR from an AWOS (Aviation Weather Observing Station).

METAR CWIK 292000Z AUTO 30015G25KT 3/4SM -SN BKN008 OVC040 M05/M08 A2992 RMK PCPN 2.8MM PAST HR SLP134


METAR Decoding Table

METAR Type of weather (Wx) report. Meteorological Aviation Report. Normally issued hourly. A special observation may be issued upon significant weather change. It would then be indicated by the word "SPECI".
CCCC = CWIK Broadview, Saskatchewan Station identifier will be 4-letter ICAO identifier.
AUTOAWOS Indicator This indicates that the report is from an AWOS autostation. Consequently, if "AUTO" is not mentioned, it means the observation was taken by a human observer.
YYGGggZ = 292000Z Date/Time29th day of the current month, 20:00 hours (8 PM) Co-ordinated Universal Time (UTC indicated by the letter 'Z').
dddffGfmfmKT = 30015G25KT WindWind is from 300 degrees True (from the NW), at 15 knots, gusting to 25 knots.
VVVVDv = 3/4SM Visibility Prevailing visibility is 3/4 of a statute mile (SM and fractions of SM with no maximum visibility value reported. AWOS sites will report a "sensor equivalent visibility".
w'w' = -SN Present Weather METAR Decoding

Present weather is light snow.

Present weather from an AWOS is currently only given as precipitation occurrence and intensity. AWOS can report one of the following METAR AUTO types:

SN - Snow
SHGR - Hail
DZ - Drizzle
RA - Rain
UP - Undetermined Type
FZDZ - Freezing Drizzle

FZRA - Freezing Rain

Note: Mixed or shower type precipitation, obstructions to vision or recent weather are among the METAR "present weather" groups NOT reported by AWOS.

Intensity can be one of the following for each type:
Light (-),(e.g. -RA, Light Rain);
Moderate ( ),(e.g. SN, Moderate Snow);
Heavy (+),(e.g. +DZ, Heavy Drizzle).

NOTE: Very light intensity is treated as no precipitation except when the Ice Accretion Sensor is also present and reporting weather (L) or (R). In this case very light intensity will be changed to light intensity.

NSNSNShshshs = BKN008 OVC040 Sky Condition

The cloud layer at 800 feet is broken, covering from 5/8 to 7/8 of the observed sky.

The next layer at 4000 feet is overcast covering, combined with the lower layer, 8/8 of the sky, as observed from the ground.

Layers are reported based on the summation of the layer amounts as observed from the surface up.

The layer amounts are reported in eighths of sky coverage (oktas) as follows:
FEW - 1 to 2,
SCT - 3 to 4,
BKN - 5 to 7,
OVC - 8.

Obscured sky (clouds not visible due to an obstruction to vision, such as fog) is indicated by vertical visibility sensor (VV) and is reported in hundreds of feet.

In AWOS reports, cloud types and amounts are not identified, cloud layers are limited to 4 layers, and clear (CLR) will be reported when no layers exist below 10000 feet.

TT/T'dT'd = M05/M08 Temperature/Dew Point

Temperature is -5°C,
Dew point is -8°C
Temperature and dew point are reported to the nearest whole °C. Negative values will be preceded by the letter "M".

APHPHPHPH = A2992 Altimeter The altimeter setting is 29.92 inches of mercury. The letter "A" prefixing the 4_digit number group also means that it is the "station pressure" (which will always be less than the sea level pressure, for a land station).
RMK = PCPN 2.8MM PAST HR Remarks Precipitation 2.8 millimetres over the past hour.
SLP = SLP134Mean Sea Level Pressure

The mean sea level pressure (MSL) sensor reading is 1013.4

The MSL pressure, is indicated in hectopascals, and will always be the last field of the METAR report, prefixed with "SLP".

METAR decoding is not as essential as it used to be, now that the "plain language" version of METARS is available. However, the short coded form is necessary because pilots of all nationalities can decode them easily.


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