METAR / TAF Decoder

What this decoder does

Type an airport identifier and it pulls that field's current observation and its terminal forecast straight from the Aviation Weather Center, then rewrites both in ordinary English: wind in words, visibility in miles, ceiling in feet above the ground, and the flight category the numbers add up to. The raw text stays on screen beside the translation, because the point is to stop needing the translation. If you would rather learn to read it cold, the guide how to read a METAR without decoding it in your head walks the same ground at a slower pace.

How to read a METAR

A METAR is an observation of what the weather is doing at one airport, issued about once an hour, usually near 55 minutes past. It is rigidly ordered, and once you know the order the groups decode themselves because each one looks like nothing else. Reading left to right you get the station, the time, the wind, the visibility, any present weather, the sky, the temperature and dew point, the altimeter setting, and finally the remarks.

A worked example

Here is a routine summer afternoon at New York Kennedy:

KJFK 011651Z 18012G20KT 10SM FEW045 SCT250 27/19 A2992 RMK AO2 SLP131 T02720194

Group	Means
KJFK	New York Kennedy, the reporting station
011651Z	The 1st of the month at 1651 UTC. The first two digits are the day, not the month
18012G20KT	Wind from 180° true at 12 knots, gusting to 20
10SM	Visibility 10 statute miles, which in a METAR means 10 or better
FEW045	A few clouds at 4,500 ft above the field
SCT250	Scattered cloud at 25,000 ft
27/19	Temperature 27°C, dew point 19°C
A2992	Altimeter 29.92 inches of mercury
RMK AO2	Automated station that can distinguish rain from snow
SLP131	Sea level pressure 1013.1 hPa
T02720194	Temperature 27.2°C and dew point 19.4°C, to a tenth of a degree

No ceiling appears anywhere in that report: FEW and SCT are not ceilings. With better than 5 SM and no broken or overcast layer, the field is VFR.

Now San Francisco on a bad morning, where the numbers change the answer:

KSFO 011656Z 28014KT 3SM BR BKN008 OVC015 14/13 A3001

Wind from 280° at 14 knots, 3 statute miles in mist, broken at 800 ft over overcast at 1,500 ft, temperature 14°C with a dew point of 13°C. The ceiling is the lowest broken or overcast layer, so it is 800 ft, and 800 ft with 3 SM is IFR. The one degree spread between temperature and dew point is the tell that the mist is not about to lift.

A third decode: a winter morning, remarks and all

The first two reports are short. Most of what frightens people off raw text is the tail of an automated report at a busy field in bad weather, so here is one in full.

KDEN 121553Z 01015G28KT 1/2SM R35L/2000FT -SN FZFG VV004 M04/M06 A2978 RMK AO2 PK WND 02033/1536 WSHFT 1510 VIS 1/4V1 SLP089 P0002 60008 T10391061 11034 21044 4/008 51012 $

Group	Means
121553Z	The 12th at 1553 UTC
01015G28KT	Wind from 010° true at 15 knots, gusting 28
1/2SM	Visibility half a statute mile
R35L/2000FT	Runway visual range for runway 35L is 2,000 ft
-SN FZFG	Light snow and freezing fog. FG means visibility below 5/8 SM, which matches the half mile
VV004	Sky obscured. An indefinite ceiling with 400 ft of vertical visibility into it, so the ceiling is 400 ft and the field is LIFR
M04/M06	Temperature −4°C, dew point −6°C
A2978	Altimeter 29.78 inHg
AO2	Automated station with a precipitation discriminator, so it can tell rain from snow
PK WND 02033/1536	Peak wind since the last report: 33 knots from 020°, at 1536Z. Seventeen minutes before this report, and 5 knots above the gust in the body
WSHFT 1510	The wind shift began at 1510Z. Add FROPA and it was a front
VIS 1/4V1	Prevailing visibility is varying between 1/4 and 1 statute mile. The half mile in the body is an average of a moving target
SLP089	Sea level pressure 1008.9 hPa
P0002	Two hundredths of an inch of water equivalent since the last METAR
60008	Eight hundredths of an inch in the past 3 or 6 hours
T10391061	Temperature −3.9°C, dew point −6.1°C. The leading 1 in each half is the minus sign
11034 21044	6 hourly maximum −3.4°C and minimum −4.4°C
4/008	Eight inches of snow on the ground
51012	Pressure tendency: 1.2 hPa higher than three hours ago, having risen then levelled off
$	Maintenance indicator. The automated system has detected that it needs service, which is a reason to weigh the rest of the report a little more carefully

Three things in that tail would change a decision. The peak wind is 33 knots against a reported gust of 28, so the crosswind you plan for is not the one in the body. The variable visibility touches a quarter mile, which is below most approach minimums. And the maintenance flag means the station reporting all of it is asking for attention.

Sky cover codes

Cloud amount is reported in eighths of the sky, and the height that follows is in hundreds of feet above the airport.

Code	Cover	Makes a ceiling?
SKC / CLR	Clear. SKC is a manual station reporting no layers; CLR is an automated station detecting none at or below 12,000 ft	No
FEW	Few (1/8 to 2/8 of the sky)	No
SCT	Scattered (3/8 to 4/8)	No
BKN	Broken (5/8 to 7/8)	Yes
OVC	Overcast (8/8)	Yes
VV004	Sky obscured, vertical visibility 400 ft	Yes
CB / TCU	Appended to a layer: cumulonimbus or towering cumulus	No change

Present weather codes

Weather groups are built in a fixed order: intensity, then descriptor, then the phenomenon itself. So +TSRA is a heavy thunderstorm with rain, -SHSN is light snow showers, and FZDZ is freezing drizzle.

Kind	Codes
Intensity	- light · nothing moderate · + heavy · VC in the vicinity, 5 to 10 SM out
Descriptor	MI shallow · PR partial · BC patches · DR low drifting · BL blowing · SH showers · TS thunderstorm · FZ freezing
Precipitation	DZ drizzle · RA rain · SN snow · SG snow grains · PL ice pellets · GR hail · GS small hail · IC ice crystals · UP unknown
Obscuration	BR mist (less than 7 SM but 5/8 SM or more) · FG fog (below 5/8 SM) · HZ haze · FU smoke · DU dust · SA sand · VA volcanic ash · BLPY blowing spray (spray is only ever coded as BLPY)
Other	PO dust whirls · SQ squalls · FC funnel cloud · +FC tornado · SS sandstorm · DS duststorm

Wind, visibility and temperature notation

Written	Means
VRB05KT	Direction variable at 5 knots, used when the wind is light or genuinely shifting
18012G20KT	From 180° at 12 knots gusting 20
15008KT 120V180	From 150° at 8, varying between 120° and 180°
00000KT	Calm
1 1/2SM	One and a half statute miles
M1/4SM	Less than a quarter of a mile
R04R/2000FT	Runway visual range: runway 04R, 2,000 ft
M03/M07	Temperature −3°C, dew point −7°C. M is the minus sign

The remarks a pilot actually meets

Everything after RMK is a US practice and it is where the useful detail hides. These are the groups and formats set out in the Federal Meteorological Handbook No. 1, chapter 12, which is the document the observing systems are built to. Plain language remarks and additive groups appear only at designated stations, so a quiet field will show a handful and a major one will show a tail like the Denver report above.

Remark	Means
AO1 / AO2	Automated station without, or with, a precipitation discriminator. AO2 can tell rain from snow
PK WND 28045/15	Peak wind since the last METAR: 45 knots from 280°, at 15 past the hour
WSHFT 30 FROPA	The wind shift began at 30 past. FROPA is added when the shift was reasonably certainly a frontal passage
VIS 1/2V2	Prevailing visibility varying between 1/2 and 2 statute miles
VIS NE 2 1/2	Sector visibility: 2 1/2 SM in the northeastern octant
TWR VIS 1 1/2 / SFC VIS 1	Visibility from the control tower, or from the surface, when it differs from the prevailing figure
CIG 005V010	Ceiling varying between 500 and 1,000 ft
BKN014 V OVC	Variable sky condition: the 1,400 ft layer is varying between broken and overcast
CIG 002 RWY11	A second ceilometer at runway 11 measures a lower ceiling than the body reports: 200 ft
RAB05E30	Rain began at 05 past and ended at 30 past. Any precipitation code can carry B and E times
TSB0159E30	The thunderstorm began at 0159Z and ended at 0230Z
TS SE MOV NE	Thunderstorm southeast of the field, moving northeast
OCNL LTGICCG OHD	Occasional in cloud and cloud to ground lightning overhead. OCNL is under 1 flash a minute, FRQ is about 1 to 6, CONS is more than 6
LTG DSNT W	Lightning detected to the west, beyond 10 but less than 30 NM. Inside 5 NM it would be TS in the body instead, and 5 to 10 NM would be VCTS
CB W MOV E / CB DSNT W	Cumulonimbus with no thunderstorm reported: within 10 SM to the west moving east, or more than 10 SM away
TCU W / ACSL SW	Towering cumulus, or altocumulus standing lenticular, in that direction within 10 SM
FG SCT000	An obscuration: fog hiding 3 to 4 eighths of the sky. A surface based obscuration always carries the height 000
VIRGA SW	Precipitation falling from cloud and evaporating before it reaches the ground, to the southwest
GR 1 3/4	Largest hailstone 1 3/4 inches across, reported in quarter inch steps
PRESRR / PRESFR	Pressure rising, or falling, rapidly at the time of observation
SLP131	Sea level pressure 1013.1 hPa. SLPNO means it is not available
P0009	Nine hundredths of an inch of water equivalent since the last METAR. P0000 is a trace
60217 / 70125	2.17 inches in the past 3 or 6 hours; 1.25 inches in the past 24, in the 1200Z report
T00261015	Temperature 2.6°C and dew point −1.5°C, to a tenth. A leading 1 in either half means below zero, a 0 means zero or above
10142 / 21001	6 hourly maximum 14.2°C; 6 hourly minimum −0.1°C
401001015	24 hour maximum 10.0°C and minimum −1.5°C
52032	Pressure tendency: 3.2 hPa higher than three hours ago, having increased steadily or unsteadily
4/021	Snow depth on the ground, 21 inches, in the 0000, 0600, 1200 and 1800Z reports
SNINCR 2/10	Snow depth rose 2 inches in the past hour, to 10 inches on the ground
933036	Water equivalent of snow on the ground, 3.6 inches, in the 1800Z report
I1004 / I6023	Four hundredths of an inch of ice accretion in the past hour; 23 hundredths in the past 6
98096	96 minutes of sunshine yesterday, in the 0800Z report
TSNO · RVRNO · PWINO · PNO · FZRANO · VISNO · CHINO	That sensor should have reported and did not: lightning detection, runway visual range, present weather, the rain gauge, the freezing rain sensor, a secondary visibility sensor, a secondary ceiling sensor
NOSPECI	A manual station that takes no SPECI, so nothing will be reported until the next METAR
$	Maintenance indicator: the automated system has detected that it needs service
FIRST / LAST	The first or last report from a part time station, so the field is about to open or has just closed

Two of those are worth a second look because they change what the rest of the report is worth. $ says the station knows it is unwell. TSNO and its relatives say a specific sensor is silent, so the absence of a thunderstorm, or of an RVR figure, is not evidence that there is none.

How to read a TAF

A TAF forecasts the conditions significant to aviation within 5 statute miles of the center of the airport's runway complex. That is the definition in NWS Instruction 10-813, the directive the forecasters write to, and it is tighter than people assume. It is issued four times a day (0000Z, 0600Z, 1200Z and 1800Z), transmitted 20 to 40 minutes before the valid period starts, covering 24 hours at most airports and 30 at the FAA designated international ones. The FAA Core 30 airports also get scheduled amendments every three hours, and any TAF can be amended at any time. A new TAF cancels the previous one for the same location and time, so a forecast issued at 1720Z is valid immediately even though its window says 1800Z. The header carries the issue time and the validity window. Everything after it is a sequence of change groups.

A worked example

KJFK 011120Z 0112/0218 18010KT P6SM FEW050

  FM011800 21014G22KT P6SM SCT040 BKN120

  TEMPO 0120/0123 4SM -TSRA BKN035CB

  FM020300 25008KT P6SM SKC

Line	Means
011120Z	Issued on the 1st at 1120 UTC
0112/0218	Valid from the 1st at 1200Z to the 2nd at 1800Z. Each half is day then hour
18010KT P6SM FEW050	To start: wind from 180° at 10, better than 6 SM, a few clouds at 5,000 ft
FM011800 …	From the 1st at 1800Z the whole picture changes: 210° at 14 gusting 22, scattered 4,000, broken 12,000
TEMPO 0120/0123 …	Between 2000Z and 2300Z, expect spells of 4 SM in light thunderstorm rain with a broken cumulonimbus deck at 3,500 ft
FM020300 …	From the 2nd at 0300Z it clears out: 250° at 8, better than 6 SM, sky clear

The TEMPO line is the one to plan around. It does not replace the 1800Z forecast; it says that inside that three hour window the field may drop to 4 SM under thunderstorms at any moment, and then come back. If you would be arriving then, you plan for the TEMPO, not for the prevailing line above it.

TAF change groups

Group	Means
FM011800	From the 1st at 1800Z: a significant and rapid change, in less than an hour, to a new set of prevailing conditions. Every element is restated, so anything an FM group leaves out is genuinely gone. NWS TAFs use FM as their only change group
TEMPO 0120/0123	Temporary fluctuations between 2000Z and 2300Z, each lasting under an hour and together covering less than half that window. An NWS TEMPO group does not exceed four hours. It is a swing on top of the prevailing forecast, not a replacement
PROB30 0915/0919	A 30% chance of a thunderstorm or precipitation event, and the wind, visibility and cloud tied to it, between 1500Z and 1900Z. PROB30 is the only PROB group in NWS TAFs, it does not exceed 6 hours, and only one appears in any FM group
WS020/24045KT	Non convective low level wind shear. 020 is the top of the shear layer in hundreds of feet above the ground, and the wind at that height is from 240° true at 45 knots. It stays prevailing until the next FM group, and it never appears in a TEMPO or PROB30 group
VCFG · VCSH · VCTS	Fog, showers or a thunderstorm in the vicinity, meaning the ring between 5 and 10 SM from the center of the runway complex. Those three are the only phenomena NWS TAFs put in the vicinity, and only in the initial period or an FM group
NSW	No significant weather: the significant weather previously forecast is expected to end. It is used in TEMPO groups, never in the initial period or an FM group
AMD / COR	The TAF has been amended, or corrected
BECMG · CAVOK · NSC	Standard internationally and not used in NWS TAFs (NWS Instruction 10-813, appendix E). Elsewhere BECMG is a gradual change across the stated window in which only the listed elements change. A US TAF does the same work with an FM group

A second TAF, with wind shear and a probability group

The first example is the common shape. This one carries the two groups people skip, and both of them are the kind that decides whether you go.

KPUB 181122Z 1812/1912 13012KT 5SM -RA SCT010 OVC035 WS020/27055KT

  FM181400 32010KT P6SM FEW008 BKN045

  PROB30 1815/1819 1SM +TSRA BR OVC007CB

Line	Means
1812/1912	Valid from the 18th at 1200Z to the 19th at 1200Z, so 24 hours
13012KT 5SM -RA SCT010 OVC035	To start: 130° at 12, 5 SM in light rain, scattered at 1,000 ft and overcast at 3,500. The 3,500 ft overcast is the ceiling, and 3,500 ft with 5 SM is MVFR on the visibility alone
WS020/27055KT	Low level wind shear with its top at 2,000 ft AGL, where the wind is 270° at 55 knots while the surface wind is 130° at 12. The wind nearly reverses and gains 43 knots inside 2,000 ft, which is what you climb out through, and it prevails until the 1400Z group
FM181400	From 1400Z: 320° at 10, better than 6 SM, few at 800 ft, broken at 4,500. The wind shear group is not restated, so it is gone
PROB30 1815/1819	Between 1500Z and 1900Z there is a 30% chance of 1 SM in a heavy thunderstorm with rain and mist, overcast cumulonimbus at 700 ft. A 30% chance of LIFR is not a forecast of LIFR, but it is the reason to carry fuel for somewhere else

Notice what the PROB30 group does to the planning rather than to the forecast. The prevailing line for your arrival is still the 1400Z group, which is comfortable. The decision the TAF is actually asking you to make is whether you can absorb the other outcome, and that question is answered with fuel and an alternate, not with a category.

What the flight categories mean

The category is a shorthand for the pair of numbers that actually matter, ceiling and visibility, and it is always set by whichever of the two is worse.

Category	Ceiling	Visibility
VFR	Greater than 3,000 ft	and greater than 5 SM
MVFR (marginal)	1,000 to 3,000 ft	and/or 3 to 5 SM
IFR	500 to below 1,000 ft	and/or 1 to below 3 SM
LIFR (low IFR)	Below 500 ft	and/or below 1 SM

These are not regulatory minimums. They are a briefing convention for coloring maps and sorting fields quickly. What you may legally do is set by the airspace and by your own personal minimums, which are usually tighter than any of these lines.

Five things that catch people out

• Heights are above the field, in hundreds of feet. BKN008 is 800 ft above the airport, not 800 ft MSL and not 8,000 ft. At a field sitting at 5,000 ft, that layer is near 5,800 ft on your altimeter.
• A low layer is not automatically a ceiling. SCT002 is two hundred feet of scattered cloud and no ceiling at all, so the field can read VFR while you cannot see the threshold. Only BKN, OVC and VV set a ceiling.
• The first two digits are the day. 011651Z is the 1st at 1651Z. A report that looks like it is from a strange month is a report you have misread.
• METAR wind is true, broadcast wind is magnetic. The number in the text and the number the tower reads you differ by the local variation, which matters when you are working out the crosswind component for a runway.
• A TAF is a forecast for a 5 mile circle. It says nothing about the ridge line you cross on the way, and the airport 30 miles down the road has its own. For the picture between fields, use the aviation weather map.

METAR or TAF: which one answers your question

A METAR tells you whether you could depart in the next few minutes. A TAF tells you whether the field will still take you when you arrive, and it is the document the 1-2-3 rule for filing an alternate is read against. Planning a flight normally means both: the METAR to decide whether to start, the TAF at the destination to decide whether to go at all, and the TAF at the alternate to prove the alternate is worth naming.

Where the data and the code tables come from

Live observations and forecasts come from the US National Weather Service Aviation Weather Center at aviationweather.gov, the same source the official briefing services read. This page is a planning aid and not an authoritative briefing: get one from Flight Service or another approved provider before you fly, and treat anything here as a head start rather than a substitute.

The code tables are not from memory. METAR and SPECI coding, the sky cover contractions, the present weather table and every remark above come from the Federal Meteorological Handbook No. 1, Surface Weather Observations and Reports (FCM-H1-2019), chapters 8 to 12, which is the standard the observing systems are built to. The TAF rules come from NWS Instruction 10-813, Terminal Aerodrome Forecasts (30 October 2024), including the groups US forecasters do not use and the 2024 removal of the old restriction on PROB30 in the first nine hours. Reporting conventions for automated stations, such as 10SM meaning 10 miles or more and CLR meaning no layer detected at or below 12,000 ft, come from the ASOS User's Guide. If a code here disagrees with one of those documents, the document is right and this page needs fixing.

FAQ

Which airport code do I use?

Use the four letter ICAO identifier: KJFK (not JFK) for New York Kennedy, KSFO for San Francisco, EGLL for London Heathrow. Most US airports are the three letter FAA identifier with a K in front, but not all: Alaska starts PA and Hawaii PH.

What is the difference between a METAR and a TAF?

A METAR is an observation: what the weather actually is at the field right now, issued about once an hour. A TAF is a forecast: what a meteorologist expects within roughly 5 statute miles of the airport for the next 24 or 30 hours. A METAR reports, a TAF predicts.

How do I find the ceiling in a METAR?

The ceiling is the height of the lowest broken (BKN) or overcast (OVC) layer, or the vertical visibility (VV) when the sky is obscured. Few (FEW) and scattered (SCT) layers are not ceilings however low they sit, so BKN008 is an 800 ft ceiling but SCT008 is not a ceiling at all.

Are cloud heights AGL or MSL?

Above ground level, measured from the airport elevation, and written in hundreds of feet. BKN008 is 800 ft above the field, not 800 ft MSL. Add the field elevation if you need an MSL number.

What does P6SM mean?

More than 6 statute miles. TAFs cap forecast visibility at 6 SM, so anything better is written P6SM rather than a figure. The matching code at the bottom of the scale is M, as in M1/4SM for less than a quarter mile.

Why does the wind in the METAR disagree with the tower?

A METAR or TAF reports wind referenced to true north. A tower, ATIS or AWOS broadcast gives it referenced to magnetic north, because that is what your heading indicator reads. The two differ by the local magnetic variation, which is about 13° on the US east coast and about 12° the other way on the west coast.

Does a TEMPO group replace the forecast?

No. TEMPO describes a condition expected to come and go, NWS Instruction 10-813 defines it as fluctuations expected to last less than an hour in each instance and, in the aggregate, to cover less than half the stated period, and an NWS TEMPO group does not exceed four hours. The prevailing forecast is whatever the initial period or the last FM group established. TEMPO sits on top of it as a swing to plan for, not as the new baseline.

What does RMK AO2 mean?

AO2 marks an automated station that can tell rain from snow; AO1 marks one that cannot. Everything after RMK is the remarks section, which is a US practice: sea level pressure as SLP131, precise temperature as T02720194, peak wind as PK WND, and a wind shift as WSHFT.

How often is this page updated?

It reads the live feed from the Aviation Weather Center each time you look up an airport. METARs are issued around 55 minutes past the hour, with a SPECI issued in between when the weather changes sharply. TAFs are issued four times a day, at 0000Z, 0600Z, 1200Z and 1800Z, with amendments as needed.

Is this an official weather briefing?

No. It is a planning aid built on the same FAA and National Weather Service data, and it is not a substitute for an official briefing. Get one from Flight Service or another approved provider before you fly.

Why is there no BECMG in a US TAF?

Because the National Weather Service does not use it. NWS Instruction 10-813 lists BECMG, CAVOK and NSC under international terminology not used in NWS TAFs, so a US TAF changes its prevailing conditions with FM groups only. BECMG is standard elsewhere, which is why a decoder still has to know it.

What does PROB30 mean, and why never PROB40?

PROB30 is a 30% chance of a thunderstorm or a precipitation event and the weather directly tied to it. NWS Instruction 10-813 states that PROB30 is the only PROB group used in NWS TAFs, so PROB40 does not appear in them although it exists internationally. A PROB30 group does not exceed 6 hours, and only one is used in any FM group.

What does WS020/24045KT mean in a TAF?

Non convective low level wind shear. The three digits after WS are the height of the top of the shear layer in hundreds of feet above the ground, so 020 is 2,000 ft, and the group gives the forecast wind at that height: from 240 degrees true at 45 knots. Once it appears it stays the prevailing condition until the next FM group or the end of the valid period, and it is never put in a TEMPO or PROB30 group.

What is the difference between BR and FG?

Only how far you can see. The Federal Meteorological Handbook No. 1 defines mist (BR) as reducing visibility to less than 7 statute miles but not below 5/8 of a mile, and fog (FG) as reducing it to less than 5/8 of a mile. Same suspended water, different code, and the dividing line is 5/8 SM.

What are the number groups at the end of the remarks?

Additive data, reported only at designated stations. A group beginning 1 is the 6 hourly maximum temperature and one beginning 2 is the 6 hourly minimum, both in tenths of a degree Celsius. A 4/ group is snow depth on the ground in whole inches, a 6 group is the 3 or 6 hourly precipitation and a 7 group the 24 hour total, both in hundredths of an inch, and a 5 group is the 3 hourly pressure tendency. P0009 on its own is 9 hundredths of an inch of precipitation since the last METAR.

Related tools: Aviation Weather Map · Personal Minimums · try it with live data for any airport →