2025年全球气候状况核心数据报告 2025 Global climate highlights

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ECMWFCommunicationSection

CopernicusTeam

EuropeanCentreforMedium-RangeWeatherForecasts,ECMWF

Robert-Schuman-Platz,53175Bonn,Germanycopernicus-

press@

PublishedJanuary14th2026updatedJanuary28th2026

(figures3and9andtheassociatedtexthavebeenupdatedtorelectfullavailabilityofglobaldatasetsfor2025).

DOI:

/10.24381/b3nm-p354

GCHeditorialteam(ECMWF):

Leadeditorandcoordination:FrancescaGuglielmo

Co-authors:JulienNicolas,FrejaVamborg,

RebeccaEmerton,AdrianSimmons,SamanthaBurgessCopyediting:ChelseaSnell

Datavisualization:AnnaLombardi

OtherContributors:MichaelBuchwitz

(UniversityofBremen),MarkParrington(ECMWF)

Communications(ECMWF):IsabelleBoscaro-Clarke,ElisabethMittelbach,EvaRemete,MaximilianLingen,

NuriaLopez,RafaelCereceda

Otherorganisations:

Blossom.it

,

EaudeWeb

,

GreenhouseCommunications

ThisGlobalClimateHighlights(GCH)reportfromtheCopernicusClimateChange

Service(C3S)providesabriefsynopsisofthestateofglobalclimatein2025,

mainlybasedondatafromtheERA5globalatmosphericreanalysisproducedby

theEuropeanCentreforMedium-rangeWeatherForecasts(ECMWF).TheGlobal

ClimateHighlightssummarisesthestateofglobalairtemperature,globalseasurfacetemperatureandseaiceinbothpolarregions.Thisreportalsoassessescurrent

globalaveragetemperaturesrelativetothe1.5°ClimitsetbytheParisAgreement,adoptedbytheConferenceofthePartiesin2015.

ERA5isoneofsixinternationaldatasetsusedtotrackglobalaveragetemperature.Inadditiontothisreport,whichincludesdatafromtheJapaneseReanalysisfor

ThreeQuartersofaCentury(JRA-3Q),further2025globaltemperatureupdates

willbereleasedbytheUKMetOffice,NASA,NOAA,BerkeleyEarthandtheWorldMeteorologicalOrganisation(WMO),basedontheirrespectivedatasets.

AcomplementaryreportontheEuropeanStateoftheClimate,providingmoredetailonconditionsinEurope,willbepublishedbyECMWFandtheC3SinApril2026,

inpartnershipwiththeWMO.

Table

ofContents

2025:thethird-warmestyearonrecord→6

Seasurfacetemperature→18

Howexceptionalwerethepastthreeyears?→22

Seaice→26

Aworldofextremeevents→28

Long-termtrendsinclimateindicators→32

ParisAgreementtargets-whereare

wenowandwherearewegoing?→34

Listoffigures

Figure1.

2025continuestheshifttowardshigherglobaltemperatures→4

Figure2.

Keytemperaturestatisticsfor2025→5

Figure3.

2025wasthethird-warmestyearonrecordaccordingtoERA5→9

Figure4.

Allmonthlytemperaturerecordshavebeenbroken

overthepastthreeyears→11

Figure5.

Anomaliesandextremesinsurfaceairtemperature→13

Figure6.

2025sawhighertemperaturesinthepolarregions→15

Figure7.

Seasurfacetemperatureremainedhighthroughout2025,despitethe

absenceofElNiñoconditions→21

Figure8.

Anomaliesandextremesinseasurfacetemperaturein2025→23

Figure9.

Byhowmuchdoannualglobaltemperaturesdeviatefromevolving

climatologicalaverages?→25

Figure10.

February2025sawlowestglobalextentofseaice→29

Figure11.

Halfoftheglobeexperiencedmoredaysthanaveragewithatleast

strongheatstressin2025→33

Toexploreallvisuals(includingsupplementaryfigures)anddownloadtheassociateddatasets,pleasevisitthe

GCH2025GraphicsGalleryonline.

Toexploredetailsondata,analysisthemethods

followed,pleasevisitthe

Aboutthedataandmethods

sectiononline.

4|Globalclimatehighlights

2025continuestheshifttowardshigherglobaltemperatures

Distributionofdailyglobalsurfaceairtemperatureanomalies(°C)from1940to2025

1940

1950

1960

1970

1980

1990

2000

2010

2020

2025

1973–76

LaNiñaevent

1991

EruptionofMtPinatubo.

Itcontributed

tothreecoolyears(1992–1994)

1998

ElNiñoevent

2023–24

ElNiñoevent

-1.5-1.0-0.50.00.5+1.0ºC+1.5ºC

Coolerthan1991–2020averageWarmerthan1991–2020average

*TheheightofeachcurveisproportionaltothenumberofdaysexperiencingagiventemperatureanomalyData:ERA5•Referenceperiod:1991‑2020•Credit:C3S/ECMWF

Figure1.Distributionofdailyglobalaveragesurfaceairtemperatureanomalies(°C)

relativeto1991–2020foreachyearfrom1940to2025.Selectedimportantclimateeventshavebeenannotated.

Datasource:ERA5.Credit:C3S/ECMWF.VisualisationinspiredbytheworkofErwanRivault(BBC).

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2025|5

Keytemperaturestatisticsfor2025

Region

Anomaly(vs1991‑2020)

Actualtemperature

Rank

Threehighestanomalies

Surfaceairtemperature

Extra-polarocean+0.38°C20.73°C3rdhighest2024:+0.51°C

2023:+0.45°C

2025:+0.38°C

Globe

+0.59°C (+1.47°Cvspre-industrial)

14.97°C

3rdhighest

2024:+0.72°C

2023:+0.60°C

2025:+0.59°C

Globalland

+0.86°C

10.08°C

2ndhighest

2024:+1.06°C

2025:+0.86°C

2023:+0.85°C

Europe

+1.17°C

10.41°C

3rdhighest

2024:+1.47°C

2020:+1.19°C

2025:+1.17°C

Seasurfacetemperature

Findmoreaboutdata,definitionsandmethodsinthe

Aboutthedataandmethods

.TheC3SEuropeanregionisdefinedas25°W‑40°E,340‑72°N.

Theextra‑polaroceanregionisdefinedas60°N‑60°S.Datasource:ERA5•Credit:C3S/ECMWF

Figure2.Keytemperaturestatisticsfor2025.Theestimatesforthegloberefertothe

averagesurfaceairtemperatureoverlandandocean,andforEuropeover

landonly.Theextra-polaroceanusedforseasurfacetemperaturereferstothe60°N–60°Sdomain.Statisticsforothergeographicdomainsareavailableinthe

GraphicsGallery

.

Datasource:ERA5.Credit:C3S/ECMWF.

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Seethechartonline.

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6|Globalclimatehighlights

2025:the

third-warmest

yearonrecord

20257

2025ranksasthethird-warmestyear

onrecord1,followingtheunprecedentedtemperaturesobservedin2023and2024.

Itwasmarginallycoolerthan2023,

while2024remainsthewarmestyearon

recordandthefirstyearwithanaverage

temperatureclearlyexceeding1.5°C

abovethepre-industriallevel.2025saw

exceptionalnear-surfaceairandseasurfacetemperatures,extremeevents,including

loods,heatwavesandwildfires.Preliminarydata2indicatethatgreenhousegas

concentrationscontinuedtoincreasein2025.

1Allfindingsinthisreport,unlessotherwisestated,arebasedontheERA5globalclimatereanalysisdatasetproducedbytheEuropeanCentreforMedium-RangeWeatherForecasts(ECMWF)andcoveringtheperiodfromJanuary1940topresentandusedforC3S’routineclimate

monitoring.Toextendtherecordbackto1850from1940weleveragelongerglobaltemperaturerecords.DatasetsotherthanERA5may

haveaslightlydifferentrankingfor2025.Theglobaltemperaturesarepresentedrelativetothepre-industriallevel,whichusesanaveragefor1850–1900fromtheIPCC6thAssessmentReport,andtoamodernreferenceperiod,usingtheaveragefor1991–2020.

2PreliminarysatellitedatafromtheCopernicusAtmosphereMonitoringService(CAMS),showthatcolumn-averagedconcentrationsofcarbondioxideandmethane,whichreached

recordlevels

in2024,continuedtoincreasein2025.Anupdateongrowthratesandconcentrationsofthesetwogases,basedonconsolidatedestimates,willbeprovidedinApril2026.

8|Globalclimatehighlights

Exceptionalheat

continuestoredefineclimaterecords:firstthree-yearaverageabove1.5°C

2025|9

2025wasthethird-warmestyearonrecordaccordingtoERA5

Globalannualsurfaceairtemperatureincreaseabovepre-industriallevelsince1850

+1.5°C

1.0

ERA5data

0.5

Othersources*

0.0

*OthersourcescompriseJRA‑3Q,GISTEMPV4,NOAAGlobalTempv6,BerkeleyEarth,HadCRUT5.Referenceperiod:pre‑industrial(1850‑1900)•Credit:C3S/ECMWF

Figure3.Globalsurfaceairtemperatureincrease(°C)abovetheaverageforthe

1850–1900designatedpre-industrialreferenceperiod,basedonseveral

globaltemperaturedatasets.*Thisfigurewasupdatedon28January2026torelectfullavailabilityofglobaldatasetsfor2025.

Credit:C3S/ECMWF.

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10|Globalclimatehighlights

2025hadaglobalaveragetemperatureof14.97°C,

0.59°Cabovethe1991-2020average,and0.13°Ccoolerthan2024,thewarmestyearonrecord.2025was1.47°Caboveanestimateofthe1850-1900

averagetemperaturedesignatedtorepresentthepre-industriallevel.Thisplaces2025asthe

third-warmestyear,marginally(0.01°C)coolerthanthesecond-warmestyear2023,accordingtoERA5.

2025wasalsothethird-warmestyearonrecord

accordingtothe

JRA-3Q

reanalysis.Theaverage

temperatureanomalyrelativeto1850–1900is1.46°CforJRA-3Q,withanabsoluteglobaltemperatureof

14.98°C.Othercentreswhoseglobaltemperature

datasets(BerkeleyEart,GISTEMPv4,HadCRUT5andNOAAGlobalTempv6)areroutinelymonitoredbyC3Splace2025aseitherthesecond-orthethird-warmestyearonrecord.Thesecentreshave2025between

1.39°C(HadCRUT5)and1.45°C(GISTEMPv4)abovethe1850–1900level,assumingthesameoffsetof

0.88°Cbetween1850–1900and1991–2020levelsasusedforERA5andJRA-3Q3.

While2025didnotreach1.5°Cabovethe

pre-industriallevel,theaverageglobaltemperaturefor2023–2025exceeded1.5°C,accordingtotheERA5dataset.Thisisthefirstthree-yearaveragetodosointheinstrumentalperiod.Theaverageforthosethreeyearsis1.52°CforERA5and1.50°CforJRA-3Q.

Theyears2023-2025standoutfromallprevious

years.Therefore,2025willbediscussednotonlyinthelong-termcontext,butalsoalongside2023and2024.

Allofthepast11years(2015–2025)rankamongthe11warmestonrecord.In2025,themonthlyglobal

averagetemperatureexceeded1.5°Cabovethe

pre-industriallevelduringsixmonthsoftheyear,fromJanuarytoApril,andagaininOctoberandNovember.Thisconcludesanalmostcontinuousseriesof21

monthsat1.5°Cabovethepre-industriallevel,startinginJuly2023,withJuly2024asthesoleexception.

3Formoreinformationonhowandwhyglobaltemperaturedatasetsdiffer,pleasesee“

Aboutthedataandmethods

”.

2025|11

Allmonthlytemperaturerecordshavebeenbrokenoverthepastthreeyears

Monthlyglobalsurfaceairtemperatureanomalies

Anomaly(ºC)

−101

Jan2025|+0.79ºC

WarmestJanuaryeverrecorded

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

198019902000201020202025

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Sep2023|+0.93ºC

Largestmonthlyanomalyeverrecorded

Data:ERA5•Referenceperiod:1991-2020•Credit:C3S/ECMWF

Figure4.Monthlyglobalsurfaceairtemperatureanomalies(°C)relativeto1991–2020

fromJanuary1979toDecember2025,plottedasaheatmap.

Datasource:ERA5.Credit:C3S/ECMWF.

Globally,January2025wasthewarmestJanuaryonrecord.March,AprilandMaywereeachthesecondwarmestforthetimeofyear.Eachmonthoftheyear,exceptFebruaryandDecember,waswarmerthanthecorrespondingmonthinanyyearbefore2023.

Globaltemperaturesforborealwinter(December2024-February2025)andspring(March-May)wereeach

thesecond-warmestforthecorrespondingseason,after2024:at0.71°C,and0.59°Crespectivelyabovethe1991-2020average.Borealsummer(June-August)andautumn(September-November)werethirdwarmestforthecorrespondingtimeoftheyear,cooleronlythan2024(warmestsummer)and2023(warmestautumn).

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12|Globalclimatehighlights

Warmerinthe

polarregions,

coolerinthetropics

In2025,annualsurfaceairtemperatureswereabovethe1991–2020average

across91%oftheglobe,thesamefractionasin2024.Nearlyhalfoftheglobe

(48%)experiencedmuchwarmerthanaverageannualtemperatures(abovethe

90thpercentileofthe1991–2020climatology4).Annualtemperatureswerethe

warmestover9%oftheEarth’ssurfacerelativetoallyearssince1979intheERA5dataset.Theseproportionswere63%(muchwarmerthanaverage)and31%5

(warmest),respectively,in2024.Whiletemperatureswerelessextremein2025thanin2024,thesefigureshighlightthepersistenceofwidespreadwarmthacrosstheglobein2025.

4Inthemapsshowing‘temperatureanomaliesandextremes’,‘warmest’meansthewarmestinthedatasetforitsmorereliableperiodfrom1979onwards,‘muchwarmerthanaverage’meanswarmerthanthe90thpercentileoftheannualtemperaturedistributionduringthe1991–2020

referenceperiod;‘aboveaverage’meanswarmerthanthe66.6thpercentile;‘nearaverage’meansbetweenthe33.3rdand66.6thpercentiles;‘belowaverage’meanscoolerthan33.3rdpercentile;‘muchcoolerthanaverage’meanscolderthanthe10thpercentile,‘coolest’meansthecoldestintheperiodfrom1979onwards.

5Thefractionsoftheglobewithrecord-hightemperaturesin2024reportedhere(forairorseasurface)areslightlylowerthanthosequotedin

theGlobalClimateHighlights2024.Thisdifferencearisesbecauserecordhighsandlowsareevaluatedoverthefull1979–2025period.Asa

result,someareasthatwereclassifiedasrecord-highin2024weresurpassedbyevenhighertemperaturesin2025,andarethereforenolongercountedasrecord-highfor2024whenusingthislongerperiod.

2025|13

Anomaliesandextremesinsurfaceairtemperature

2025

20232024

CoolestMuchcooler

thanaverage

Coolerthanaverage

Nearaverage

WarmerMuchwarmerWarmestthanaveragethanaverage

Data:ERA51979-2025•Referenceperiod:1991-2020•Credit:C3S/ECMWF

Figure5.Anomaliesandextremesinsurfaceairtemperaturein2025(largemap)andin

2023and2024(smallermaps).Colourcategoriesrefertothepercentilesofthetemperaturedistributionsforthe1991–2020referenceperiod

4

.Theextreme

(‘coolest’and‘warmest’)categoriesarebasedonrankingsfor1979–2025.

Datasource:ERA5.Credit:C3S/ECMWF.

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14|Globalclimatehighlights

Landareasthatweremuchwarmerthanaveragein

2025includedthetropicalregionsoftheAmericas,

northeasternCanada,largepartsofAfrica,the

MaritimeContinent,largepartsofEuropeand

extratropicalAsia,aswellasmostofGreenlandandAntarctica.AnnualairtemperaturesoverlandreachedrecordhighsoverthewesternUnitedStates,easternGreenland,northernEurope,westernRussia,centralAsia,easternChina,andAntarctica.Theannualair

temperatureaveragedoverallgloballandareaswasthesecondwarmestonrecord,at0.86°Cabove

average,0.20°Ccoolerthantherecordsetin2024and0.01°Cwarmerthanin2023.

Cooler-than-averagetomuchcooler-than-average

landregionsin2025includedeasternSouthAmerica,partsofwesternmostandsouthernAfrica,mostof

India,partsofsoutheastAsiaandfar-easternRussia.Thecooler-than-averageairtemperaturesoverthe

tropicalPacificrelectedpatternsinseasurface

temperature(SST)associatedwithneutralElNiñoSouthernOscillation(ENSO)orLaNiñaconditions6.

SSTconditionsin2025arediscussedinmoredetailinthe

Seasurfacetemperatures

section.

Temperatureanomalies,relativetothe1991–2020

period,averagedoverfivelatitudebandsprovide

furtherinsightintolong-termwarmingtrendsacross

theglobe,aswellasnotableregionaldifferencesin

2025comparedwith2023and2024.Allregionsshowaclearlong-termwarmingtrend,althoughvariabilityislargerintheAntarcticregion.

Inthetropics,thetemperatureanomalyin2025

(+0.29°C)waslowerthanin2023(+0.53°C)and

2024(+0.68°C).Thisrelectsthepersistenceof

neutralENSOconditionsorperiodsofweakLaNiñathroughout2025,incontrasttothestrongElNiño

eventthatinluencedpartsof2023and2024.LessextremetemperaturesinthetropicalAtlanticandIndianOceansalsocontributed.

Inthenorthernmid-latitudes,thetemperatureanomalyin2025(+0.84°C)waslowerthanin2024(+0.99°C)

butidenticaltothevalueobservedin2023.Both

2023and2025rankedasthesecond-highestyearsonrecordforthisregion.Incontrast,temperatureanomaliesinthepolarregionswerenotablyhigh.

ThiswasparticularlyevidentintheAntarcticregion,wheretheanomaly(+1.06°C)reachedarecordhighin2025.IntheArctic,theanomaly(+1.37°C)wasthesecond-highestonrecord,behind2016(+1.59°C).

Inthesouthernmid-latitudes,thetemperature

anomalyin2025(+0.42°C)wasthesameasinbehind2016,withbothyearsjointlyrankingasthewarmestonrecordfortheregion.

Thisregionalbreakdownoftemperatureanomalies

showsthattheloweranomalyinthetropics

reducedtheglobalaveragein2025,whilerecordornear-recordwarmthinmostotherregionspartlyoffsetthiseffect,resultingin2025beingonly0.01°Ccoolerthan2023globally.

6ElNiñoSouthernOscillation(ENSO)isanaturalclimatepatternthatinvolvesperiodsofwarmer-than-average(ElNiño)orcooler-than-average(LaNiña)seasurfacetemperatures(SSTs)inthecentralandeasterntropicalPacific.PeriodswhenSSTsareclosetoaveragearereferredtoas‘ENSO-neutral’or‘neutralENSOconditions’.

2025|15

2025sawhighertemperaturesinthepolarregions

Annualsurfaceairtemperatureanomaliesin2025

60ºN

20ºN

20ºS

60ºS

CoolerthanaverageWarmerthanaverage

0.6ºC

0.4

0.2

0.0

-0.2

-0.4

-4ºC-2ºC-1ºC+1ºC+2ºC+4ºC

Globalannualsurfaceairtemperature

anomaliessince1979

198019902000201020202025

Data:ERA5•Referenceperiod:1991-2020•Credit:C3S/ECMWF

1.0ºC

Arctic(60ºN-90ºN)

0.0

-1.0

1.0ºC

Northernmid-latitudes(20ºN-60ºN)

0.0

-1.0

Tropics(20ºS-20ºN)1.0ºC

0.0

-1.0

Southernmid-latitudes(60ºS-20ºS)1.0ºC

----0.0

-1.0

1.0ºC

Antarctic(90ºS-60ºS)

0.0

-1.0

198019902000201020202025

Figure6.(Topleft)Mapofannualsurfaceairtemperatureanomaliesin2025.

(Bottomleft)Timeseriesofglobalannualtemperatureanomaliesfrom1979to

2025.(Right)Timeseriesofannualtemperatureanomaliesaveragedoverfivelatitudebandsfrom1979to2025.Allanomaliesarecalculatedrelativetotheaverageforthe1991–2020referenceperiod.

Datasource:ERA5.Credit:C3S/ECMWF.

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16|Globalclimatehighlights

Thethird-warmestyearforEurope

2025|17

ForEurope,2025wasthethird-warmestyearon

record,withanaveragetemperatureof10.41°C,

1.17°Cabovetheaverageforthe1991-2020referenceperiod.Thiswas0.30°Cbelowtherecordof2024

(1.47°Caboveaverage)andonly0.02°Ccooler

thanthevaluefor2020(1.19°Caboveaverage),thesecond-warmestyear.Onlyonemonthoftheyear,

March,wasthewarmestforEurope,withanaveragetemperatureof6.03°C,2.41°Cabovethe1991-2020averageforMarch,0.26°CwarmerthanthepreviouswarmestMarchin2014.

Winter2025(December2024toFebruary2025)wasthejointsecondwarmestfortheseason,at1.46°Cabovethe1991-2020average,significantlycooler

thanthewarmestEuropeanwinterin2020

(2.84°Caboveaverage).

Fortheyearasawhole,temperatureswereabove

averageacrossEuropeandmuchaboveaverageinmostregions,withtheexceptionofcentralpartsofthecontinent.TheeasternnorthAtlantic,theNorthSearegionincludingnorthernBritainandpartsof

Scandinavia,thesouthwesternMediterranean,andwesternmostRussiasawrecord-warmtemperatures.

18|Globalclimatehighlights

Seasurface

temperature

Seasurface

temperatures

remainedhigh,

despiteENSO-neutralconditions

2025|19

Seasurfacetemperatureremainedhighthroughout2025,despitetheabsenceofElNiñoconditions

Monthlyseasurfacetemperatureanomaliesrelativeto1991-2020

Global*(60ºS-60ºN)

1995200020052010201520202025

Niño3.4region

0..7°CC0..30..0

-0..3

4.0°C

1997–98

2015–16

2023–242..0

0.0

-200

1998–2001

1995200020052010201520202025

*Excludingpolarregion.Datasource:ERA5•Credit:C3S/ECMWF

Figure7.Monthlyseasurfacetemperature(SST)anomaliesaveragedovertheextra-polar

ocean(60°S–60°N;top)andovertheNiño3.4region(5°N–5°S,170°–120°W;

bottom)intheequatorialPacific.Anomaliesarerelativetothemonthlyaveragesforthe1991–2020referenceperiodforthecorrespondingmonth.

Datasource:ERA5.Credit:C3S/ECMWF.

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20|Globalclimatehighlights

Theseasurfacetemperature(SST)averagedovertheextrapolaroceans(60°S–60°N)remainedhistorically

highthroughout2025,despitetheabsenceofElNiñoconditions.Thiscontrastswith2023and2024,whenastrongElNiñoeventinluencedSSTsforseveralmonthsofthesecondhalfof2023,peakinginDecember

2023,withSSTsremaininghighthroughout2024and

theaverageSSTreachingrecordhighs.Theannual

averageSSTfor2025was20.73°C,0.38°Cabovethe1991–2020average.Itrankedasthethird-higheston

record,0.13°Cbelowtherecordsetin2024and0.07°Cbelow2023,thesecond-highestyear.Thismakes2025thewarmestLaNiñayearonrecordbothintermsof

globalairtemperatureandSST.

Atthemonthlyscale,theaverageSSTwasthesecondwarmestonrecordforthetimeofyearfromJanuary

toMay(behind2024),thethirdwarmestfromJune

toOctober(behind2023and2024),andthefourth

warmestinNovemberandDecember(behind2023,2024,and2015,whichwasalsoinluencedbya

strongElNiñoevent).IntheequatorialPacific,SSTs

werecoolerthanaverageearlyintheyear,relectingashort-lived,weakLaNiñaeventinDecember2024andJanuary2025.NeutralENSOconditionsprevailedfromMarchtoJuly.Cooler-than-averageSSTs

developedagainfromAugust,leadingtoareturnto

weakLaNiñaconditionsinOctoberthatpersisteduntiltheendoftheyear.

TheannualSSTanomaliesfor2025showapatternconsistentwithLaNiña–likeconditions,with

near-averagetocooler-than-averageSSTsacross

muchoftheeasternandcentraltropicalPacific.Apartfromlimitedregionswithcooler-than-averageSSTs

inthenorthwesternandsouthernIndianOcean,the

northeasternNorthAtlantic,andthesoutheastern

Pacific,SSTswereaboveaverageacrossmostoftheworld’soceans.About9%oftheextrapolaroceans

experiencedrecord-highannualSSTs,substantially

lessthanin2024(25%

4

),mainlybecauseofless

extremeSSTsinthetropicalAtlanticandIndian

Oceansthaninthepreviousyear.In2025,record-highSSTsweremainlyfoundinthewesternand

northwesternPacific,theIndianOceansectoroftheSouthernOcean,thenortheasternNorthAtlanticandadjacentNorthSea,NorwegianSeaandBarentsSea,aswellaspartsofthewesternMediterraneanSea.

Beyondrecordvalues,SSTsweremuchwarmerthanaverage(abovethe90thpercentileoftheclimatology)over42%oftheextrapolaroceans,comparedto59%in2024,underscoringthecontinuedwidespread

warmthofthesurfaceoceans.

Anotablefeatureof2025SSTswastherecordwarmthacrosslargepartsofthewesternNorthPacific.Severalfactorsareknowntohavecontributedtotheexceptionalwarmthoftheworld’soceanssince2023(see

How

exceptionalwerethepastthreeyears?

section

below).Atthesametime,thewarmSSTpatternacrossthewesternNorthPacificobservedin2025isconsistentwiththecombinationofLaNiñaconditionsanda

negativephaseofthePacificDecadalOscillation(PDO)thatcharacterisedmuchoftheyear.Thiscombinationisknowntofavour

warmSSTanomalies

inthisocean

basin.ThehighSSTsalsorepresentthecontinuation

ofa

markedwarmingoftheNorthPacific

sincearound2013–2014,whichhasbeenlinkedinparttochangesinoceanmixed-layerdepth.

2025|21

Anomaliesandextremesinseasurfacetemperaturein2025

NortheasternAtlantic

Record-warmover

largeareas

NorthwesternPacific

Mostlymuchwarmer

thanaverageorrecord-warm

EquatorialPacific

TropicalAtlanticandIndianOcean

Lessextremethanin2024

Cooler-than-averagereflectingENSO-neutralorweakLaNiñaconditions

Seaice&iceshelves

CoolestMuchcooler

thanaverage

Cooler

thanaverage

Nearaverage

Warmer

thanaverage

Muchwarmerthanaverage

Warmest

Data:ERA51979-