A Guide to (De)coding METAR-format Weather Observations

Syntax:

ID TIME WINDS VISIBILITY WEATHER CLOUDS TEMP/DEW ALTIMETER REMARKS

ID is the 4 letter ID, Kxxx for US

TIME is a full time ddhhmmZ

WINDS is the wind group dddssKT or dddssGggKT

VISIBILITY is the visibility group vvSM or vvKM

WEATHER is the weather group iiddppooxx
ii is intensity group
- light
moderate (nothing)
+ heavy
VC in the vicinity

dd is the descriptor group
MI shallow
PR partial
BC patches
DR low drifting
BL blowing
SH shower
TS thunderstorm
FZ freezing

pp is the precipitation group
DZ drizzle
RA rain
SN snow
SG snow grains
IC ice crystals
PE ice pellets
GR hail
GS small hail/snow pellets
UP unknown

oo is the obscuration group
BR mist
FG fog
FU smoke
VA volcanic ash
DU dust
SA sand
HZ haze
PY spray

xx is the misc group
PO dust whirls
SQ squalls
FC funnel cloud/tornado/waterspout
SS duststorm

CAVOK = clear skies, unlimited visibility

CLOUDS are the cloud levels ccchhhtt
ccc is the coverage
CLR or SKC = clear
FEW = 1/8 coverage
SCT = 2,3,4/8 coverage
BKN = 5,6,7/8 coverage
OVC = overcast
VV = vertical visibility for obscuration
hhh is the height of base in 30m or 100ft increments
tt is an optional type
CU = cumulus
CB = cumulonumbus
TCU = towering cumulus
CI = cirrus

TEMP/DEW is the temperature and dewpoint in Celsius
negative values are preceded with a M (M03 = -3)

ALTIMETER is the altimeter setting
Qpppp = altimeter in whole mb
Apppp = altimeter in .01 in Hg

REMARKS:
AO1 = AMOS station
AO2 = ASOS station
SLPppp = Sea level pressure in .1 mb (142 = 1014.2 mb)
Tttttdddd = Current temperature/dewpoint in .1C
T01720144 = temp=17.2C, dew=14.4C, first digit 1 for negative
1xxxx = 6 hour max temp in .1C, first digit 1 for negative
2nnnn = 6 hour min temp in .1C, first digit 1 for negative
4/sss = Snow coverage in inches
4xxxxnnnn = 24 hour max/min temps in .1C, first digit 1 for negative
5tppp = Pressure tendency in .1 mb for 3 hours
6pppp = 6 hour precipitation in .01 inches
7pppp = 24 hour precipitation in .01 inches
8/lmh = Cloud type for low, medium, high
933sss = New snow coverage, water equivalent
98mmm = Equivalent sunshine for day in minutes
CITY tt = City temperature
PCPN pppp = 1 hour precipitation
PK WND sss/nn = Peak wind, sss is speed, nn is the time
PRESFR = Pressure falling rapidly
PRESRR = Pressure rising rapidly
SNOINCR xxx = Snow increasing rapidly
WSHFT nn = Wind shift at time nn
plus more...

Some samples:

KLAF 030445Z 35007KT 15SM SKC 17/13 A2986

KLAF = Station Identifier
030445Z = Time (ddhhmmZ)
35007KT = Winds (350 deg at 7 knots)
15SM = Visibility (15 statute miles)
SKC = Clear skies
17/13 = Temperature/Dewpoint in Celsius
A2986 = Altimieter setting (29.86 in Hg)

KLAF 021915Z COR 22010KT 7SM TSRA BKN055 30/17/ A2974 RMK T W MOVG NE

TSRA = Weather (TS-Thunderstorm RA-Rain)
BKN055 = Cloud level (Broken at 5500 feet)

KLAF 021950Z 30008KT 7SM BKN065CB -RA 25/21 A2976 RMK TE40

BKN065CB = Cloud level (Broken at 6500 feet with cumulonimbus)

LTCC 022250Z 32003KT CAVOK 24/10 Q1011 NOSIG=

CAVOK = Cloud/Visibility (OK=Clear with unlimited visibility)
Q1011 = Altimeter setting (1011 mb)

KFHU 022336Z 33011G25 35SM TS VCSH FEW040 SCT060CB BKN100 BKN250
31/14 A3003 RMK WSHFT 27 FRQ LTGICCG TS N MOV W SHRA N AND
NE-SE=

33011G25 = Winds (330 at 11 Gusts to 25)
TS VCSH = Weather (TS=Thunderstorm, VC=Vicinty, SH=Shower)
FEW040 = Clouds (FEW=few clouds or 1/8 coverage at 4000 feet)

KIND 022356Z 26009KT 10SM CLR 24/20 A2973 RMK AO2 SLP062 60000
T02440200 10317 20228 56009 $=

AO2 = ASOS station
SLP062 = Sea level pressure (062=1006.2 mb)
60000 = 6 hour precipitation (0000=trace)
T02440200 = Current temperature/dewpoint (temp=0244=24.4C,dew=0200=20.0C)
10317 = 6 hour max temp (317=31.7C)
20228 = 6 hour min temp (228=22.8C)
56009 = Pressure tendency (6009=falling .9 mb in last 3 hours)

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above Courtesy of Dan Vietor