METAR decoding in Europe

METAR - Aerodrome Actual Met Report

The METAR is a report giving the actual weather conditions at an aerodrome at the time of the report.
METAR's are issued every 30 minutes during the opening hours of the aerodrome.

METAR Decode

A European METAR signal may comprise up to 10 components - preceded by a 3 component identifier.

Identifier Components

1. Report Type - METAR

2. Location Indicator - ICAO four letter aerodrome code.
3. Time - The time of the observation in UTC (GMT) in hours and minutes followed by the letter Z (the
universal indication that GMT time is being reported).

Example: METAR EHAM 1050Z

Let us look at a typical example:

METAR EHAM 1050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

Note here that not all the 10 weather components are shown. If no data is recorded at the time of
observation then certain fields (RVR, weather, wind shear) may be omitted altogether. In addition the cloud
component may be used more than once if several cloud layers are present.

I'll continue with a more detailed description of each field and we shall come back to the METAR for EHAM
(Amsterdam) at the end.

METAR Component Decode

1. Wind

Wind is given as direction in degrees true followed by the average wind speed.
Example:24015KT - indicates that the wind is blowing from the southwest at 15 kts..
Note: KMH (Kilometres per hour) or MPS (Metres per second) may also be found in this group e.g
34025KPH.

If the wind is gusting this will be shown by a further group of figures preceded by the letter G. Example:

24015G27KT

this indicates that the average wind is 240 at 15 kts but gusts to 27 kts are recorded.

If the wind is calm then 00000KT will be shown.

A variable wind direction will be shown by VRB e.g. VRB02KT would indicate that the wind was only 2 kts
but would not be blowing from any fixed direction.

If the wind is greater than 3 kt and the direction is varying by 60 degrees or more then the actual values
must be recorded. Example:

31015G27KT 280V360

shows that the wind is blowing from the northwest at 15 kts with gusts to 27 kts but that the wind direction is
varying from 280 to 360 degrees. Not very nice...

2. Visibility

Visibility is recorded as a four figure group in metres (2000 metres is roughly 1 nm).
If 0000 is shown it would indicate that the visibility is less than 50 metres.
If 9999 is shown it indicates that the visibility is 10 km or more.

If local conditions vary greatly then two groups may be displayed showing the visibility variation in different
sectors e.g.

1000NW 6000S

- showing that the visibility to the northwest of the aerodrome is only 1000 metres but is 6 km to the south.
3. RVR (Runway Visual Range)

Runway Visual Range is an indication of the real visibility as measured down the runway either
electronically or manually. RVR is taken when the Met visibility drops below 1500 metres and it will therefore
only be shown occasionally in METAR reports. RVR visibility will always be prefixed by the letter R followed
by the runway for which the value has been taken. Example:

R24/1200 - RVR for runway 24 is 1200 metres

It may be of interest to you to know that the RVR value recorded is significant to pilot operations. If the RVR
value is below that published for the approach procedure then the aircraft CANNOT MAKE AN APPROACH.
The aircraft must either remain in the holding pattern until the weather improves or it must divert.
4. Weather

Weather is identified by one or more two letter groups. The full list is not very long so I shall include them all
here - even the more obscure phenomena ...

DZ Drizzle
RA Rain
SN Snow
GR Hail
SQ Squalls

GS Small Hail
SG Snow Grains
IC Diamond Dust
PE Ice Pellets

BR Mist
FG Fog
 FU Smoke
HZ Haze

VA Volcanic Ash
DU Widespread dust
SA Sand
SS Sandstorm
DS Duststorm
FC Funnel Cloud

We may also describe these in more detail with a two letter prefix.

MI Shallow
BC Patches
DR Drifting
BL Blowing
SH Showers
TS Thunderstorm
FZ Supercooled (Freezing)

Slight or heavy conditions may also be described by using a - or + sign

before the two letter code. Examples of some combinations:

RA = Rain
SHRA = Rain Showers
FZFG = Freezing fog
-DZ = Slight Drizzle
+SHSN = Heavy snow showers
MIFG = Shallow fog
CB Cumulonimbus
TCU Towering CB

5. Cloud

Usually this is a six figure group and one that most of you will already recognise. The group consists of
three letters that describe the cloud cover followed by three figures for cloud height ABOVE AERODROME
LEVEL. Cloud amount is given as;

FEW Few. This indicates 1 or 2 oktas of cloud.

SCT Scattered. This indicates 3 or 4 oktas of cloud.
BKN Broken. This indicates 5 to 7 oktas of cloud.

OVC Overcast. This indicates 8 oktas (solid cloud cover).

Cloud height is given by the next three figures which show the altitude in hundreds of feet. i.e. 040 is 4000
ft, 004 is 400 feet, 200 is 20,000 ft. Examples:

SCT020 - Scattered at 2000 ft.

BKN005 - Broken cloud at 500 feet.
OVC250 - Overcast at 25,000 feet.
A METAR may contain several cloud layers so you may get: SCT025 BKN070 BKN120 -

showing scattered cloud at 2500 ft, broken cloud at 7000 feet and again at 12,000 feet.

SKC (Sky Clear) will be used if no cloud layers are observed.

CAVOK will also be used if no cloud exists below 5000 ft AND the visibility is greater than 10 km AND there
is no fog, precipitation or snow.
CB will be used to emphasise Cumulonimbus formation - BKN015CB
TCU will be used to signify Towering CB formation

In conditions of fog when the cloud cover cannot be seen then the vertical visibility will be reported using VV
as the code.
e.g. VV003 = vertical visibility 300 feet.
If the fog is so bad that no measurement can be taken then you may possibly see VV/// in a METAR.
6. Temperature and Dew Point

Temperature and Dew Point are both measured in Centigrade. A minus value is preceded by the letter M.
Examples:

25/12 = Temp 25°C, Dew Point 12°C, or

00/M02= Temp 0°C, Dew Point -2°C.
7. QNH (Barometric Pressure)

QNH (zračni tlak na letališču reduciran na morski nivo!) is rounded down to the next whole millibar and
reported as a four figure group preceded by Q. If the value is less than 1000mbs then the first digit will be 0.

Examples;

Q0996, Q1030.

To explain this further may I just add that if you set the QNH value on your altimeter then the height
displayed on the instrument will be your height above sea level. If you are on the ramp then your altimeter
should read airport elevation.

One other side factor of pressure is on aircraft performance. If QNH is low then an aircraft will perform much
more badly (less lift, slow climb, poor engine performance) because it is operating in less dense air.
8. Recent Weather

This may be included if appropriate using the weather codes above, prefixed with RE (for recent).
Example RERA for recent rain..
9. Wind Shear

Again this will only be included if appropriate. The code WS is used followed by the runway affected.
Example:

WS LDG RWY28L or WS TKOF RWY08

10. Trend

This is only available at selected airfields. It is intended to indicate significant changes of weather in the two
hours after the observation is made. If the change is temporary then TEMPO is used followed by the
predicted conditions. If the change is permanent them BECMG (Becoming) will be used. Example:

TEMPO 3000 SHRA = temporary visibility 3000 metres with rain showers.
BECMG 33035KT = becoming 35 kts of wind from 330.
NOSIG = no significant changes in weather.
Putting it all together

OK, that's the details so lets take a look at some examples. First we look again at the METAR I copied from
Amsterdam earlier:

METAR EHAM 1050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

This is a typical METAR and is quite easy to decode.

The report was measured at 1050 UTC and it shows that Amsterdam was reporting a wind of 240 at 15 kts,
the visibility was 9km (9000m), it was raining, cloud was scattered at 2500 ft and broken at 4000 ft.
Temperature was 10C and dew point 9C, the sea level pressure (QNH) was 1010 mb and there was no
significant change expected in the next two hours.

This would seem to indicate the passing of a slow frontal system across the area with only a slow
improvement in weather conditions during the day. A look at nearby airport METAR information showed
similar conditions.

A METAR can be quite brief sometimes:

METAR EGLL 0920Z 26005KT CAVOK 15/14 Q1013 NOSIG

This shows that Heathrow at 0920 UTC was giving a slight 5kt westerly wind with no cloud or visibility
problems, a moderate temp of 15C and normal pressure of 1013.

On the other hand, in bad weather a METAR can look much different....

Have a look at this one at Dusseldorf in poor visibility:

METAR EDDL 1550Z 26005KT 0550 R23L/0450 FZFG OVC002 M02/M02 Q0994 BECMG OVC005

which shows a met visibility of 550 metres and a RVR reading on 23L of 450 metres in freezing fog with a
200 ft cloudbase. Temp and Dew Point are down at -2C and the trend is of little consolation with the cloud
only forecast to increase to 500 feet.

Here is one for Dublin:

METAR EIDW 0900Z 24035G55KT 210V270 1700 +SHRA BKN007 OVC015CB 08/07 TEMPO 3500

A nasty cold and windy day with strong gusty 35 kt wind up to 55kts at times and swinging from 210 to 270
degrees. Visibility is reduced to 1700 metres in heavy rain showers and a low cloud cover of 700 feet and
solid Cumulonimbus at 1500 ft to add to the misery. At least they expect the visibility to increase to 3500
metres even if only temporarily.

METAR LFPG 1250Z 28010KT 8000 HZ SCT070 BKN240 28/22 Q1003 NOSIG
 TAF
In meteorology and aviation, TAF is a format for reporting weather forecast information, particularly as it relates
to aviation. "TAF" is an acronym of Terminal Aerodrome Forecast or, in some countries, Terminal Area
Forecast. Generally a 24-hour forecast, it complements and uses similar encoding to METAR reports.

This TAF example is from Calgary International Airport, Calgary, Alberta, and was released on October 19,
2006 at 2038 UTC:

TAF CYYC 192038Z 192118 17008KT P6SM SCT020 OVC080 TEMPO 2203 P6SM -SHRA
BECMG 2223 24007KT
FM0300Z 32010KT P6SM SCT007 BKN060
FM0600Z 33015KT P6SM SCT010 BKN040 TEMPO 0612 5SM -RASN BR OVC010
FM1200Z 34015G25KT P6SM SCT010 OVC030 TEMPO 1218 2SM -SHSN OVC010
RMK NXT FCST BY 00Z=

 TAF indicates that the following is a terminal area forecast.

 CYYC indicates that the report came from Calgary International Airport.
 192038Z indicates that the report was issued at 2038 UTC on the 19th of the month.
 192118 indicates that the report is valid from 2100 UTC on the 19th until 1800 UTC on the following
day.
 17008KT indicates that the wind is forecasted in the first part of the forecast (2100 to 0300 UTC) to be
from 170 degrees at 8 knots.
 P6SM indicates that visibility is forecasted to be at least six statute miles. Forecasted visibility of six
miles or more is always referred to as P6SM. If meters are used there are no additional characters
(same as METAR).
 SCT020 OVC080 indicates that clouds are forecasted to be scattered at 2000 feet and overcast at 8000
feet.
 Additionally a min. and max. temperature group can be used here. The format is:
TXTtTt/HHZTNTtTt/HHZ - Forecast Max and Min temperature
TX - Indicator for Maximum temperature
TtTt - Temperature value in Celsius
TN - Indicator for Minimum temperature
HH - Forecast hour, i.e. the time(hour) when the temperature is expected
Z - Time Zone indicator, Z=GMT.
 3 modifieres can be used to identify the time of specific events: TEMP (Temporary fluctuation in some
of the elements lasting for periods of 30 minutes or more but not longer than one hour), BECMG
(Becoming - Used to indicate a gradual change in some of the forecast elements) and FMHHmm
(From).
 TEMPO 2203 P6SM -SHRA indicates that between 2200 and 0300 there may be at times light rain
showers with visibility of at least six statute miles.
 BECMG 2223 24007KT indicates that a wind shift to 240 degrees at 7 knots is forecasted to occur
between 2200 and 2300 UTC.
 FM0300Z 32010KT P6SM SCT007 BKN060 indicates that beginning at 0300 UTC the wind will be from
320 degrees at 10 knots, visibility will be at least six statute miles, and clouds will be scattered at 700
feet and broken at 6000 feet.
 FM0600Z 33015KT P6SM SCT010 BKN040 TEMPO P612 5SM -RASN BR OVC010 indicates that
beginning at 0600 UTC the wind will be from 330 degrees at 15 knots, visibility will be at least six
statute miles, and clouds will be scattered at 1000 feet and broken at 4000 feet. There is forecasted to
be at times between 0600 and 1200 hours visibility at 5 statute miles, rain showers, snow showers, and
mist with an overcast layer of cloud at 1000 feet.
 FM1200Z 34015G25KT P6M SCT010 OVC030 TEMPO 1218 2SM -SHSN OVC010 indicates that
beginning at 1200 UTC the wind will be from 340 degrees at 15 knots gusting to 25 knots, visibility will
be at least six statute miles, and clouds will be scattered at 1000 feet and overcast at 3000 feet. There
is also forecasted to be at times between 1200 and 1800 hours light snowshowers, visibility of two
statute miles, and an overcast layer of cloud at 1000 feet.
 RMK NXT FCST BY 00Z indicates that the next forecast will be issued by 0000 UTC.