[{"data":1,"prerenderedAt":399},["ShallowReactive",2],{"learn-\u002Flearn\u002Fhow-to-read-a-taf":3,"learn-nav-\u002Flearn\u002Fhow-to-read-a-taf":361},{"id":4,"title":5,"body":6,"date":290,"description":291,"draft":292,"extension":293,"faqs":294,"howTo":304,"keyTakeaways":312,"meta":313,"navigation":314,"path":315,"quiz":316,"seo":342,"series":343,"seriesOrder":282,"sources":344,"stem":358,"topic":359,"__hash__":360},"learn\u002Flearn\u002Fhow-to-read-a-taf.md","How to read a TAF",{"type":7,"value":8,"toc":280},"minimark",[9,21,27,32,46,68,72,78,81,136,139,142,146,150,153,208,212,236,240,265,269],[10,11,12,13,20],"p",{},"A ",[14,15,19],"a",{"href":16,"className":17},"\u002Flearn\u002Fglossary#gt-taf",[18],"glossary-link","TAF"," is a coded forecast of the weather expected at an aerodrome over a fixed period, and reading one well is what turns a pile of numbers into a plan for your flight.",[22,23,24],"blockquote",{},[10,25,26],{},"This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.",[28,29,31],"h2",{"id":30},"forecast-not-observation","Forecast, not observation",[10,33,34,35,39,40,45],{},"A TAF (Terminal Aerodrome Forecast) is a ",[36,37,38],"strong",{},"prediction",", where a ",[14,41,44],{"href":42,"className":43},"\u002Flearn\u002Fglossary#gt-metar",[18],"METAR"," is a measurement. That single distinction shapes everything about how a TAF is written. Because the future is uncertain, the code includes ways to say \"this will change\", \"this might change\", and \"expect this for short spells\", which a METAR never needs.",[10,47,48,49,55,56,61,62,67],{},"Like the METAR, the TAF is an international code form defined in the ",[14,50,54],{"href":51,"rel":52},"https:\u002F\u002Flibrary.wmo.int\u002Frecords\u002Fitem\u002F35713-manual-on-codes-international-codes-volume-i-1",[53],"nofollow","WMO Manual on Codes (WMO No. 306)"," under the meteorological service framework of ",[14,57,60],{"href":58,"rel":59},"https:\u002F\u002Fstore.icao.int\u002Fen\u002Fannex-3-meteorological-service-for-international-air-navigation-1",[53],"ICAO Annex 3",". A TAF describes the weather expected close to the aerodrome, not across the whole region. The ",[14,63,66],{"href":64,"rel":65},"https:\u002F\u002Fwww.faa.gov\u002Fair_traffic\u002Fpublications\u002Fatpubs\u002Faim_html\u002Fchap7_section_1.html",[53],"FAA AIM"," makes a US TAF a station forecast for about a 5 statute mile radius of the centre of the runway complex; the wider 5 to 10 statute mile band (roughly 8 km) is the AIM's \"in the vicinity\" (VC) range, used for phenomena reported near rather than at the aerodrome. Either way, the TAF is a vicinity forecast, so do not read it as an area or en route product.",[28,69,71],{"id":70},"a-worked-example","A worked example",[10,73,74],{},[75,76,77],"code",{},"TAF EGLL 181100Z 1812\u002F1918 24012KT 9999 BKN025 FM181500 27015G25KT SCT030 TEMPO 1818\u002F1822 6000 -RA BKN012 PROB30 1900\u002F1904 3000 BR",[10,79,80],{},"Reading it through:",[82,83,84,98,108,114,124,130],"ul",{},[85,86,87,89,90,93,94,97],"li",{},[75,88,19],{}," is the report type, ",[75,91,92],{},"EGLL"," the aerodrome (Heathrow), and ",[75,95,96],{},"181100Z"," the issue time: the 18th at 1100 UTC.",[85,99,100,103,104,107],{},[75,101,102],{},"1812\u002F1918"," is the ",[36,105,106],{},"validity period",": valid from the 18th at 1200 UTC until the 19th at 1800 UTC, a 30-hour TAF. Each part is a day-and-hour pair, so read both halves carefully across midnight and month ends.",[85,109,110,113],{},[75,111,112],{},"24012KT 9999 BKN025"," is the prevailing forecast at the start: wind from 240 degrees at 12 knots, visibility 10 km or more, broken cloud at 2500 ft.",[85,115,116,119,120,123],{},[75,117,118],{},"FM181500 27015G25KT SCT030"," is a ",[75,121,122],{},"FM"," (from) group: from the 18th at 1500 UTC the wind veers to 270 degrees at 15 knots gusting 25, and cloud becomes scattered at 3000 ft.",[85,125,126,129],{},[75,127,128],{},"TEMPO 1818\u002F1822 6000 -RA BKN012"," says that, temporarily between the 18th at 1800 and 2200 UTC, expect visibility down to 6000 m in light rain with broken cloud at 1200 ft.",[85,131,132,135],{},[75,133,134],{},"PROB30 1900\u002F1904 3000 BR"," gives a 30 per cent probability of visibility 3000 m in mist between the 19th at 0000 and 0400 UTC.",[10,137,138],{},"The units follow the same regional conventions as the METAR: metres and hectopascals in the ICAO form, statute miles and inches of mercury in the US form.",[10,140,141],{},"Try it yourself below. Paste a TAF into the decoder and it explains each group, including the validity period and the FM, BECMG, TEMPO and PROB change groups. It only explains the text you enter; it does not fetch live weather.",[143,144],"report-decoder",{"type":145},"taf",[28,147,149],{"id":148},"the-change-groups","The change groups",[10,151,152],{},"The grammar of a TAF lives in its change groups, defined by the same WMO and ICAO code form:",[82,154,155,167,176,196],{},[85,156,157,162,163,166],{},[36,158,159,161],{},[75,160,122],{}," (from)"," marks a rapid and more or less complete change at a stated time, written as ",[75,164,165],{},"FMDDHHMM",". Everything after it replaces the previous conditions until the next change group.",[85,168,169,175],{},[36,170,171,174],{},[75,172,173],{},"BECMG"," (becoming)"," marks a gradual change expected to take place over the stated period, with the new conditions reached by the end of that window and then continuing.",[85,177,178,184,185,189,190,195],{},[36,179,180,183],{},[75,181,182],{},"TEMPO"," (temporary)"," marks temporary fluctuations expected to come and go. Per the ",[14,186,188],{"href":51,"rel":187},[53],"WMO"," and US ",[14,191,194],{"href":192,"rel":193},"https:\u002F\u002Faviationweather.gov\u002Fdata\u002Fmetar\u002F",[53],"NWS"," conventions, each instance lasts less than about an hour and the fluctuations in total cover less than half the stated period; in between, conditions return to the prevailing forecast.",[85,197,198,207],{},[36,199,200,203,204],{},[75,201,202],{},"PROB30"," and ",[75,205,206],{},"PROB40"," give a 30 or 40 per cent probability of the conditions that follow. Only those two values are used: a higher likelihood is written as the main forecast, and a lower one is not considered worth a group.",[28,209,211],{"id":210},"how-long-a-taf-is-valid","How long a TAF is valid",[10,213,214,215,218,219,203,222,227,228,231,232,235],{},"Routine TAFs are commonly valid for ",[36,216,217],{},"24 or 30 hours"," and are issued at fixed times, as the ",[14,220,66],{"href":64,"rel":221},[53],[14,223,226],{"href":224,"rel":225},"https:\u002F\u002Fwww.metoffice.gov.uk\u002Fservices\u002Ftransport\u002Faviation\u002Fregulated\u002Ftraining-resources-for-aviation\u002Fmetars-and-tafs",[53],"Met Office"," both describe, though some aerodromes issue shorter ones. When a forecast is updated before its normal time, an amended TAF is issued and marked ",[75,229,230],{},"AMD","; a corrected one is marked ",[75,233,234],{},"COR",". Both supersede the version before them, so always brief from the latest issue.",[28,237,239],{"id":238},"common-pitfalls","Common pitfalls",[82,241,242,253,259],{},[85,243,244,252],{},[36,245,246,203,248,251],{},[75,247,182],{},[75,249,250],{},"PROB"," are not invitations to ignore the bad weather."," Plan for the worse case inside the window, especially around your planned arrival and any alternate.",[85,254,255,258],{},[36,256,257],{},"A TAF is vicinity only."," Pair it with the latest METAR for current conditions and with area or significant-weather products for the route.",[85,260,261,264],{},[36,262,263],{},"Mind the validity boundaries."," A flight that lands just after the TAF expires is not covered by it.",[28,266,268],{"id":267},"in-pilot-efb","In Pilot EFB",[10,270,271,272,275,276,279],{},"Pilot EFB shows the ",[36,273,274],{},"decoded"," TAF alongside the ",[36,277,278],{},"raw"," text, with the raw forecast always kept so you can trace each change group back to the original code. A forecast you have already pulled stays readable offline, because your device holds what you have saved; fetching a fresh or amended TAF needs a connection. Pilot EFB is offline-first, not a certified Electronic Flight Bag, so cross-check the official forecast before you commit to a plan.",{"title":281,"searchDepth":282,"depth":282,"links":283},"",2,[284,285,286,287,288,289],{"id":30,"depth":282,"text":31},{"id":70,"depth":282,"text":71},{"id":148,"depth":282,"text":149},{"id":210,"depth":282,"text":211},{"id":238,"depth":282,"text":239},{"id":267,"depth":282,"text":268},"2026-06-16","Decode a Terminal Aerodrome Forecast, including the FM, BECMG, TEMPO and PROB change groups, the validity period, and how a forecast differs from a METAR observation.",false,"md",[295,298,301],{"q":296,"a":297},"What is the difference between a TAF and a METAR?","A TAF is a forecast of the weather expected at an aerodrome, where a METAR is an observation of what was measured. Because the future is uncertain, a TAF uses change groups to say something will, might, or temporarily will change, which a METAR never needs.",{"q":299,"a":300},"What do FM, BECMG, TEMPO and PROB mean in a TAF?","FM (from) marks a rapid, more or less complete change at a stated time; BECMG (becoming) marks a gradual change over a period; TEMPO marks temporary fluctuations that come and go; and PROB30 or PROB40 give a 30 or 40 per cent probability of the conditions that follow.",{"q":302,"a":303},"How long is a TAF valid?","Routine TAFs are commonly valid for 24 or 30 hours and issued at fixed times, though some aerodromes issue shorter ones. An amended forecast is marked AMD and a corrected one COR, and both supersede the version before them, so always brief from the latest issue.",{"name":5,"steps":305},[306,307,308,309,310,311],"Identify the report: TAF, the aerodrome, and the issue day and time in UTC.","Read the validity period, given as two day-and-hour pairs such as 1812\u002F1918, reading carefully across midnight and month ends.","Decode the prevailing forecast at the start: the wind, visibility, weather and cloud expected.","Apply the change groups: FM, BECMG, TEMPO and PROB each modify the forecast over their stated periods.","Mind the units: metres and hectopascals in the ICAO form, statute miles and inches of mercury in the US form.","Check for amendments: an AMD or COR TAF supersedes the earlier one, so brief from the latest issue.",null,{},true,"\u002Flearn\u002Fhow-to-read-a-taf",[317,326,334],{"q":318,"options":319,"answer":324,"explanation":325},"How does a TAF differ from a METAR?",[320,321,322,323],"A TAF is an observation; a METAR is a forecast","A TAF is a forecast; a METAR is an observation","They are the same report under two names","A TAF only covers the en route phase of a flight",1,"A TAF is a forecast of the weather expected at an aerodrome, where a METAR is an observation of what was measured.",{"q":327,"options":328,"answer":324,"explanation":333},"In the validity group 1812\u002F1918, what does the 1812 part mean?",[329,330,331,332],"18 December","The 18th of the month at 1200 UTC","A visibility of 1812 metres","18 hours and 12 minutes of flight","Each part is a day-and-hour pair, so 1812\u002F1918 is valid from the 18th at 1200 UTC until the 19th at 1800 UTC.",{"q":335,"options":336,"answer":324,"explanation":341},"What does PROB30 mean in a TAF?",[337,338,339,340],"A 30-knot wind is expected","A 30 per cent probability of the conditions that follow","The forecast runs for 30 hours","Conditions improve by 30 per cent","PROB30 gives a 30 per cent probability of the conditions that follow; only PROB30 and PROB40 are used.",{"title":5,"description":291},"decode-the-weather",[345,347,350,352,354,356],{"label":346,"url":64},"FAA Aeronautical Information Manual, Chapter 7 Section 1 (Meteorology)",{"label":348,"url":349},"FAA Aviation Weather Handbook (FAA-H-8083-28B)","https:\u002F\u002Fwww.faa.gov\u002Fregulationspolicies\u002Fhandbooksmanuals\u002Faviation\u002Ffaa-h-8083-28b-aviation-weather-handbook",{"label":351,"url":224},"UK Met Office: METARs and TAFs",{"label":353,"url":58},"ICAO Annex 3: Meteorological Service for International Air Navigation",{"label":355,"url":51},"WMO No. 306: Manual on Codes, Volume I.1",{"label":357,"url":192},"NOAA\u002FNWS Aviation Weather Center: TAF and METAR data","learn\u002Fhow-to-read-a-taf","Weather","9SjuLiPWOIE5F9nqVr1bRgSJsrPFNCD4HHqvTWT4Tq4",{"related":362,"newer":380,"older":385,"series":391},[363,369,373],{"path":364,"title":365,"description":366,"date":367,"topic":359,"draft":292,"minutes":368,"series":312,"seriesOrder":312},"\u002Flearn\u002Freading-a-surface-analysis-chart","How to read a surface analysis chart","Decode a surface analysis chart: isobars and the pressure gradient, highs and lows, warm, cold and occluded fronts, and what the big picture tells you before you read the METAR.","2026-06-20",3,{"path":370,"title":371,"description":372,"date":367,"topic":359,"draft":292,"minutes":368,"series":312,"seriesOrder":312},"\u002Flearn\u002Fthe-international-standard-atmosphere","The International Standard Atmosphere (ISA)","What the ICAO International Standard Atmosphere is, its sea-level values and lapse rate, and how ISA deviation underpins altimetry, performance and density altitude.",{"path":374,"title":375,"description":376,"date":377,"topic":359,"draft":292,"minutes":378,"series":343,"seriesOrder":379},"\u002Flearn\u002Fhow-to-read-a-sigmet-and-airmet","How to read a SIGMET and an AIRMET","What SIGMETs and AIRMETs warn of, the phenomena codes, how long each stays valid, and a worked SIGMET decoded field by field, with the ICAO baseline and the US differences.","2026-06-18",5,4,{"path":381,"title":382,"description":383,"date":384,"topic":359,"draft":292,"minutes":378,"series":343,"seriesOrder":324},"\u002Flearn\u002Fhow-to-read-a-metar","How to read a METAR","A plain-language guide to decoding a METAR field by field, with a worked example and the EASA\u002FUK and FAA differences that trip pilots up.","2026-06-17",{"path":386,"title":387,"description":388,"date":389,"topic":390,"draft":292,"minutes":379,"series":312,"seriesOrder":312},"\u002Flearn\u002Funderstanding-notams","Understanding NOTAMs","What a NOTAM is, how the ICAO format and Q-line are built, the difference between NOTAMN, NOTAMR and NOTAMC, and how to deal with NOTAM overload.","2026-06-15","Briefing",{"slug":343,"title":392,"part":282,"total":378,"prev":380,"next":393},"Decode the weather",{"path":394,"title":395,"description":396,"date":397,"topic":359,"draft":292,"minutes":398,"series":343,"seriesOrder":368},"\u002Flearn\u002Fhow-to-read-an-atis","How to read an ATIS","What the ATIS broadcast contains, how the information letter and runway-in-use work, how it differs from a METAR, and the EASA\u002FUK and FAA conventions that trip pilots up.","2026-04-07",7,1781989193112]