Will 2026 be the hottest year on record?

- [2026-01-14] NASA/GISS released 2025 annual global temperature data (Release 26-003); since record-keeping began in 1880, the hottest year on record remains 2024, and global temperatures in 2025 were cooler than 2024, with average temperatures of 1.19 degrees Celsius above the 1951-1980 baseline . Earth's global surface temperature in 2025 was slightly warmer than 2023 – but within the margin of error: the two years are effectively tied . [Source: science.nasa.gov/earth/explore/earth-indicators/global-temperature/] - [2025-01-10] NASA's official record year remains 2024, whose GISS LOTI anomaly was confirmed at 1.28 degrees Celsius (2.30 degrees Fahrenheit) above the agency's 20th-century baseline — this is the exact "1.28°C" figure named in the market's resolution rule. [Source: sedvme.gsfc.nasa.gov/earth/giss/pressreleases] - [2026-04-21] Carbon Brief's Q1 "state of the climate" report found the year is virtually certain to be one of the four warmest on record and, currently, has a 19% chance of surpassing 2024 as the warmest year on record , with a best estimate that 2026 would land as the second-warmest year, between 2024 and 2023 . [Source: carbonbrief.org, state-of-the-climate-strong-el-nino...] - [2026-07-24] Carbon Brief's mid-year update reported as 2026 passed its halfway point, one of the most rapidly intensifying El Niño events in the modern record was taking shape, and the chance of a new global record had risen to 35% – a near-doubling in four months , with the first six months of 2026 being the third-warmest start to a year on record, behind only 2024 and 2025 . [Source: carbonbrief.org, state-of-the-climate-rapidly-developing-el-nino...] - [2026-08-04] CNN reported that because of the ongoing El Niño's predicted record peak, it is even more likely that 2026 and 2027 will set records for the warmest years on record, with record warm global sea surface temperatures already in place for at least two months . [Source: cnn.com/2026/08/04/weather/el-nino-strongest-record-hottest-year-climate] - [2026-09-15] The Climate Adaptation Center reported that August 2026 global temperatures tied July 2023 as the hottest August on record at 1.65°C above pre-industrial level , amid a rapidly strengthening "Very Strong" El Niño (Niño-3.4 anomaly >+3.0°C). - [2026-09-15] Per the same report, real-time tracking from Climate Brink showed Niño-3.4 running at +2.94°C as of September 11, 2026 and forecast to peak near +4°C in November , which would be the strongest El Niño on record; WMO has declared "exceptionally high likelihood of nearly 100%" it persists through February 2027 (per same article). - [2026-09-15] The same source notes a key uncertainty for this market: Carbon Brief's estimate puts 2026 around the current record of 1.51°C above preindustrial levels but projects 2027 at approximately 1.71°C — which would "comfortably set a new record" with a 92% chance of doing so , implying 2026 is expected to fall just short of a new record, with the bigger warming boost landing in 2027 (consistent with historical lag between El Niño peak and global temperature peak). - [2026-09-15] The Climate Adaptation Center article stresses dataset-dependent uncertainty on the 2026-vs-record question: odds "of a 2026 record range from 66% in NASA and Berkeley Earth data down to just 9-13% in the ERA5 and JRA-3Q reanalyses," underscoring that even by late summer 2026 no dataset had confirmed a new record. - [2026-09-26] NASA/GISS's own data page confirms monthly releases continue on schedule with the most recent GISTEMP update covering through July/August 2026, and no annual determination for 2026 has been made (nor could be, since the year is not yet complete). [Source: data.giss.nasa.gov/gistemp/] - [2026-09-26, ongoing] No NASA GISS press release or SVS feature announcing 2026 as a record year, or confirming/denying it, has yet been issued — the annual GISTEMP determination is not expected until the routine January-2027 release (based on the pattern seen for 2023, 2024, and 2025 releases, all issued in the second week of January of the following year). BOTTOM LINE: As of late September 2026, NASA GISS's confirmed annual record remains 2024 (1.28°C above 1951-1980 baseline), with 2025 coming in cooler (1.19°C); 2026 has been running as the 3rd-4th warmest year-to-date, boosted late in the year by a historically strong, rapidly intensifying El Niño, giving it a real but still-uncertain (independent estimates ranging roughly 19-66%) chance of surpassing 2024/1.28°C — while most forecasters (Carbon Brief, UK Met Office) currently expect 2026 to land as the second-warmest year, with the bigger record more likely to fall in 2027 due to the typical lag between El Niño peak and global temperature response. NOT FOUND: An official NASA GISS annual determination for 2026 (not yet possible, data incomplete); a Carbon Brief "state of the climate" update newer than early-to-mid August 2026 giving a revised percentage chance of a 2026 record incorporating September El Niño data; the exact September 2026 monthly GISTEMP LOTI anomaly value.

- [2026-01-14] NASA/GISS confirmed Earth's global surface temperature in 2025 was slightly warmer than 2023, but within the margin of error, and since record-keeping began in 1880, the hottest year on record remains 2024. GISS put 2025 at 1.19°C above 1951-1980 (2024 was 1.28°C above that baseline), meaning the Kalshi threshold ("above 2025 value and 1.28°C") effectively requires 2026 to beat the 2024 record in GISS's series. - [Base rate, historical]: New annual GISS/global records have been set roughly once every 3-8 years historically (e.g., 1998, 2005, 2010, 2014, 2015, 2016, 2020, 2023, 2024), almost always coinciding with a strong El Niño year (as in 2015-16, 2023-24) or its immediate aftermath — a back-to-back record is common but not universal (2024 followed 2023; 2016 followed 2015; but 2020/2021/2022 did not beat 2016 until 2023). - [2026-07-24] Carbon Brief's independent probabilistic model (which correctly forecasted 2023/2024 record odds in real time) initially gave 2026 just a 7% chance of a new record using March data, rising as El Niño forecasts strengthened: using March data, 2026 had just a 7% chance of setting a new record; that rose to 16% in April, 24% in May, 27% in June and 35% using the latest data in mid-July. - [2026-07-24] Crucially for this NASA-specific market, Carbon Brief's dataset-by-dataset breakdown showed materially higher odds in NASA's own series than in other trackers: Running the same projection gives odds of a 2026 record of around two-in-three for Berkeley Earth (66%) and NASA GISTEMP (65%), but only 35% for HadCRUT5, 24% for NOAA and just 13% and 9% for the ERA5 and JRA-3Q reanalyses, respectively. - [2026-07-24] Carbon Brief's central (average-of-six-datasets) estimate still favored second place, not a record: This central estimate would make 2026 the second-warmest year on record, just below 2024 (1.52C) and ahead of 2023 (1.43C) and 2025 (1.41C). - [2026-08-12] A Time/Polymarket recap synthesizing Carbon Brief's update framed the shift explicitly: Carbon Brief gives 2026 a 65% chance of setting a record in NASA's dataset... Driven by the developing El Niño, climate models and prediction markets have converged on the same ominous forecast: what looked like a long shot this spring is now the likeliest outcome—a record-hot 2026. - [2026-05-28] Earlier in the year, betting markets and forecasters were much more skeptical: On Polymarket, 2026 is currently priced at a 31% implied probability of becoming the hottest year on record and a 60% implied probability of becoming the second-hottest year on record. This illustrates how quickly odds have moved (roughly doubling) as the El Niño intensified between spring and mid-summer 2026. - [2026-09-21] The ENSO driver behind the revised odds has continued to intensify past Carbon Brief's July analysis: A very strong 2026 El Niño is intensifying, with Niño 3.4 hitting +3.0°C (mid-Sept) and subsurface heat surging... All 22 forecast models agree it will strengthen further, staying "very strong" through winter 2026–27... Could rank among the strongest El Niño events on record. This is stronger than Carbon Brief's July projections, suggesting the NASA-specific record odds (already 65% in July) have likely risen further by September. - [2026-05-26] The WMO's decadal outlook, a comparable "expert consensus" reference class, judged a record within a 5-year window (not necessarily 2026 specifically) as more likely than not: It is likely (86% chance) that one year between 2026 and 2030 will surpass 2024 as the warmest year on record... Annual global mean near-surface temperatures during 2026–2030 are predicted to range between 1.3°C and 1.9°C above the 1850-1900 average. This spreads the record probability across five years rather than concentrating it in 2026 alone. - [2025-12-18] James Hansen's group, an outlier but historically influential forecaster, had initially projected 2026 would dip and 2027 would set the record: We project a global temperature record of +1.7°C in 2027... we expect a minimum 12-month running-mean temperature of about +1.4°C to be reached in the first half of 2026, after which global temperature should begin a rise that will continue into 2027, reaching a new record high. Hansen's team viewed 2027, not 2026, as the more likely record year based on ENSO lag effects — a view echoed by Carbon Brief's own 2027 projection of 92% record odds. - [2026-07-24] Carbon Brief's own analysis agrees the El Niño's peak impact typically lags into the following year: If these projections bear out, the 2020s will have delivered new global temperature records in 2023, 2024 and 2027 – and potentially 2026 too – with a number of individual years well above the 1.5C threshold. The long-term warming trend...has increased from around 0.18C per decade in the early 2000s to around 0.27C per decade today. BOTTOM LINE: The base-rate/outside-view picture shows record-year probability estimates for 2026 have risen sharply and consistently through the year (from ~7% in March to ~35% cross-dataset and ~65% in NASA's own GISTEMP series by July, per Carbon Brief's model) as an exceptionally strong, still-intensifying El Niño took hold; historically, records typically fall either in the El Niño onset year or (more often) the following year, so while 2026 has a real and rising chance in NASA's GISS series specifically, the field's central/consensus expectation as of mid-2026 still leaned toward 2026 as "second warmest" with 2027 favored as the more likely record-setter. NOT FOUND: No official Carbon Brief or comparable "state of the climate" update from September 2026 was located giving an explicit, updated numeric record-probability (cross-dataset or NASA-specific) reflecting the further El Niño intensification reported by IRI in mid-September 2026; no Kalshi-specific market pricing/odds for this exact contract were found in search results.

- [2026-09-24] Berkeley Earth's August 2026 update (published by Robert Rohde and Zeke Hausfather) reports that August 2026 was the warmest August on record, with a global average of 1.71 ± 0.11 °C above the 1850–1900 average, ahead of August 2023 , and every model in the September ensemble now projects a record-strength El Niño event, with roughly a 98% chance on the relative index that adjusts for background ocean warming . Source: berkeleyearth.org/august-2026-temperature-update/ - [2026-09-24] Critically for the YES case, the same Berkeley Earth release states plainly: "2026 is likely to be a new record warmest year" and their headline number for that assessment is 2026 now has roughly a 93% chance of becoming the warmest year on record, up from about 69% a month ago (per the article's own summary bullet). This is a large jump from Carbon Brief's mid-July NASA-specific figure of 65% cited in colleague reports, and it is the newest, most authoritative numeric record-odds estimate available as of this writing. - [2026-09-24] Ocean heat is the specific mechanism driving this: Berkeley Earth found ocean temperatures were 1.296 ± 0.097 °C above the 1850–1900 average — not only the warmest August on record for ocean surfaces, but nominally the warmest month of any kind ever recorded for the oceans , meaning the record-setting heat is concentrated in the ocean component that dominates the annual global mean and is slow to reverse. - [2026-09-24] The report also flags that in absolute terms, August 2026 was nominally the 2nd warmest month in the entire record… essentially tied with July 2023, and August 2026 came in above July 2026, which is itself unusual and reflects how much warmth the developing El Niño added over the course of the summer — i.e., the seasonal cycle is being overridden by El Niño forcing earlier than typical, a sign the warming is intensifying faster than in prior record years (2015-16, 2023-24). - [2026-09-24] The Niño 3.4 trajectory underpinning this forecast is now the strongest on record for this point in the year: even after adjusting for the more than +1 °C increase in the mean ocean temperature, the monthly average in August is nearly +2 °C, which is the threshold for a very strong ("super") El Niño, with temperatures expected to continue climbing until peaking between November and January . A peak that large, arriving before year-end (not just after), directly supports the argument that enough of its warming effect will land within calendar 2026 itself to break the record, rather than being deferred entirely to 2027. - [2026-08-13] Corroborating the acceleration, Bloomberg reported in mid-August (before the September jump) that an unusually powerful El Niño is raising the odds that 2026 will surpass 2024 as the world's hottest year on record , quoting Berkeley Earth's Robert Rohde: "It will be giving us weather conditions that we would normally expect to be a decade or more away. It's going to be a big deal." Source: bloomberg.com/news/articles/2026-08-13. - [2026-09-11] Carbon Brief's own DeBriefed newsletter confirms via Copernicus that August 2026 was independently verified as a joint record: August of this year tied with July 2023 as the hottest month ever recorded globally... temperatures for the month were 1.65C above pre-industrial levels , cross-validating Berkeley Earth's finding with a second major dataset (Copernicus/ERA5) at essentially the same time. Source: carbonbrief.org/debriefed-11-september-2026. - [2026-09-14] NASA/GISS itself added new infrastructure specifically built to track this question in real time: its data page confirms on September 14, 2026, GISS added a new GISTEMP GMSTA page displaying various estimates of the current and next years' annual Global Mean Surface Temperature Anomaly, calculated with respect to the pre-industrial period 1850-1900 — a signal that GISS itself now sees the current/next-year record question as significant enough to warrant a dedicated live-tracking product. Source: data.giss.nasa.gov/gistemp/. - [2026-07-24 / mechanism] Carbon Brief's own dataset breakdown (cited by colleagues) already showed NASA GISTEMP-specific record odds (65%) running far above the cross-dataset average (35%) in July, because GISS's land-heavy, Arctic-sensitive methodology tends to amplify El Niño-driven warming more than reanalyses like ERA5 — a structural reason the NASA-specific contract (this market's actual resolution source) is more YES-prone than "average of all datasets" framings would suggest. - [2026-08-17] Independent commentary summarizing Berkeley Earth's July release stated that across 14 operational seasonal forecast systems, every model projects a very strong event at its peak, with a multi-model weighted median peak Niño 3.4 anomaly near +4.0 °C, most likely in November 2026, far above the roughly +2.75 °C peak of prior events , reinforcing that this El Niño's magnitude is unprecedented in the observational record, not merely comparable to 2015-16 or 2023-24. BOTTOM LINE: The single most likely path to YES is that the still-intensifying, record-strength El Niño (Niño 3.4 already record-high for this time of year and forecast near +4.0°C by November) pushes enough of its warming into the September–December 2026 window — via record ocean heat already realized in August — that NASA's GISTEMP annual mean for 2026 exceeds both 2025 and the 1.28°C 2024 threshold; Berkeley Earth's September 24 update, the newest and most direct evidence available, now puts the record-year probability at 93%, a sharp jump from 69% a month earlier and far above Carbon Brief's July NASA-specific estimate of 65%, making this the strongest and most current evidentiary support for YES. NOT FOUND: An official NASA GISS press release or SVS feature explicitly stating 2026 GISTEMP record odds or a September 2026 monthly GISTEMP LOTI anomaly value (GISS's own monthly release lags Berkeley Earth's by several weeks); a Carbon Brief "state of the climate" or DeBriefed update newer than September 11 giving a revised, explicit NASA-specific numeric probability incorporating the very latest (post-September 24) El Niño intensification.

- **[2026-09-23]** Carbon Brief's latest analysis (updated 23 Sept) explicitly states that the seasonal forecast models "predicted temperatures slightly warmer than observed this summer, with real-world observations for August coming in around 0.3C below forecasts" — a documented warm bias in the El Niño models underpinning the bullish 2026-record narratives. [carbonbrief.org/analysis-super-el-nino-reaches-remarkable-all-time-record] - **[2026-09-21]** The same Carbon Brief piece reaffirms the core mechanism working against a 2026 record: global temperatures typically lag in the tropical Pacific by around three months, so an El Niño event peaking in November and December 2026 will have its largest warming influence on 2027 , with the historical analogs 1997-98, 2015-16 and 2023-24 all showing the record fell in the year *after* El Niño onset, not the onset year itself. - **[2026-09-23]** Carbon Brief's own bottom line as of its most recent quarterly assessment (referenced in the 21 Sept piece) is that "Carbon Brief’s most recent 'state of the climate' quarterly analysis found 2026 on track to be the warmest or second-warmest year on record" — i.e., even the outlet driving most of the "record" narrative still hedges with "or second-warmest," not a confirmed record. - **[2026-09-21]** Carbon Brief flags an unprecedented-event caveat that cuts against confident record projections: "No seasonal forecast system has ever been verified against an event of this size, because none has ever occurred," undermining the reliability of the very El Niño-peak forecasts (≈4.1°C Niño 3.4) that are driving 2026-record odds upward. - **[2026-09-26]** IRI/Columbia's ENSO forecast update shows El Niño probability holding at 100% only through Feb 2027 before "declining to 61% in MJJ 2027... consistent with the tendency for strong El Niño events to weaken rapidly after reaching their peak" — supporting the "peak-then-crash" mechanism that historically shifts the record year to the year following peak, not the peak year itself (2026). - **[2026-08-14]** Climate Impact Company's ENSO diagnostics report projects "the rapid decline in Super El Nino intensity during northern hemisphere spring and shift to a potential moderate strength La Nina middle of 2027... the NCEP CFS V2 forecast also projects a rapid descent in El Nino strength" — reinforcing that this El Niño's warming boost to global temperature is heavily backloaded into very late 2026 and early 2027, leaving limited time for it to lift the full-year 2026 GISS annual average above 2024's 1.28°C. - **[2026-05-13]** Fox Weather's analysis of the historical record notes "In looking at the previous Super El Niño years since 1970, four out of five instances were followed immediately by La Niña the next year" — a pattern (2015-16→weak 2016 La Niña; 1997-98→strong prolonged La Niña) historically associated with the *following* year, not the El Niño-onset year, capturing the peak global-temperature response. - **[2026-07-27]** Even Carbon Brief's own central, multi-dataset estimate for 2026 — cited by colleagues as "second warmest" — comes from a report whose title itself frames 2026 as headed for second place: "Carbon Brief estimates that the global average temperature in 2026 will be between 1.37C and 1.58C above pre-industrial levels, with a best estimate 1.47C. This puts 2026 on track to likely be the second warmest year on record" . - **[2026-07-09]** Copernicus/ERA5 — a dataset independent of NASA GISS but highly correlated with it — confirms 2026 has consistently ranked second, not first, at the monthly level all year: June 2026 was "the second-warmest June on record globally, with an average surface air temperature of 16.54C" , following May 2026 which was also "the second warmest May on record, with global air temperatures 1.42°C above pre-industrial levels" — both trailing 2024, the year GISS must be beaten. - **[2026-07-01]** Copernicus Marine Service's mid-year bulletin shows the ocean-heat engine behind any late-2026 warming surge is itself running behind the 2024 pace, not ahead of it: "the first half of 2026 was the second warmest on record, with an average sea-surface temperature of approximately 20.94°C, slightly below the record set in 2024 (at around 21.04°C)" — meaning 2026 enters its record-critical final quarter already trailing 2024's ocean-heat trajectory. - **[2025-01-10 / 2026 base]** Historically, GISS has failed to produce a new record in the immediate El Niño-onset year even during comparably dramatic ENSO transitions (e.g., 2015 vs. 2016, 2023 vs. 2024), and NASA's own annual determination is never made until the routine second-week-of-January release — meaning that even if late-2026 monthly anomalies spike, no official NASA confirmation of a 2026 record is possible before market close, and Kalshi's contract could expire on the April 2027 fallback date without a definitive Yes trigger if data are delayed or ambiguous. BOTTOM LINE: The mechanism most likely to produce a NO is the well-documented three-month lag between El Niño peak (expected Nov 2026–Feb 2027) and its maximum global-temperature effect, which historically pushes the actual temperature record into the year *after* the El Niño onset (as in 1998, 2016, 2024) rather than the onset year itself; multiple independent, recent sources (Carbon Brief's own Sept 21 update, Copernicus monthly bulletins, IRI's ENSO decay forecast) still frame 2026 as "on track for second place" with 2027 as the more probable record-setter, and even the bullish NASA-specific 65-66% odds cited by colleagues come from a model whose own recent verification showed a warm bias (August observations 0.3°C below forecast). NOT FOUND: An official NASA GISS statement or SVS release addressing 2026 specifically (none exists yet, by design); a Carbon Brief "state of the climate" update newer than 21 September 2026 with a revised NASA-specific percentage (the next full quarterly update is explicitly slated for "early October" per the Sept 21 piece); confirmed September 2026 GISTEMP LOTI monthly anomaly value.