Home/Blog2025 was the 2nd warmest year (a distant 2nd behind 2024) in the 47-year satellite record
The Version 6.1 global average lower tropospheric temperature (LT) anomaly for December, 2025 was +0.30 deg. C departure from the 1991-2020 mean, down from the November, 2025 value of +0.43 deg. C. (In the following plot note that the 13-month centered-average trace [red curve] has now been updated after several months of not being updated).
The Version 6.1 global area-averaged linear temperature trend (January 1979 through December 2025) remains at +0.16 deg/ C/decade (+0.22 C/decade over land, +0.13 C/decade over oceans).
2025 Ended the Year as a Distant 2nd Warmest Behind 2024
The following plot shows the ranking of the 47 years in the UAH satellite temperature record, from the warmest year (2024) to the coolest (1985). As can be seen, 2024 really was an anomalously warm year, more than can be attributed to El Nino alone.
The next plot shows how our UAH LT yearly anomalies compare to those posted on the WeatherBell website (subscription required) for the surface air temperatures from NOAA’s Climate Data Assimilation System (CDAS). There is pretty good correspondence between the two datasets, with LT having warm outliers during major El Ninos (especially 1987, 1998, 2010, and 2024). This behavior is due to extra heating of the troposphere (which LT measures) during El Nino by enhanced deep moist convection in the tropics when the tropical Pacific Ocean surface warms from reduced upwelling of cold water from below, an effect exaggerated by the several-month lag of tropospheric warming behind surface warming during El Nino:
The following table lists various regional Version 6.1 LT departures from the 30-year (1991-2020) average for the last 24 months (record highs are in red).
| YEAR | MO | GLOBE | NHEM. | SHEM. | TROPIC | USA48 | ARCTIC | AUST |
| 2024 | Jan | +0.80 | +1.02 | +0.57 | +1.20 | -0.19 | +0.40 | +1.12 |
| 2024 | Feb | +0.88 | +0.94 | +0.81 | +1.16 | +1.31 | +0.85 | +1.16 |
| 2024 | Mar | +0.88 | +0.96 | +0.80 | +1.25 | +0.22 | +1.05 | +1.34 |
| 2024 | Apr | +0.94 | +1.12 | +0.76 | +1.15 | +0.86 | +0.88 | +0.54 |
| 2024 | May | +0.77 | +0.77 | +0.78 | +1.20 | +0.04 | +0.20 | +0.52 |
| 2024 | June | +0.69 | +0.78 | +0.60 | +0.85 | +1.36 | +0.63 | +0.91 |
| 2024 | July | +0.73 | +0.86 | +0.61 | +0.96 | +0.44 | +0.56 | -0.07 |
| 2024 | Aug | +0.75 | +0.81 | +0.69 | +0.74 | +0.40 | +0.88 | +1.75 |
| 2024 | Sep | +0.81 | +1.04 | +0.58 | +0.82 | +1.31 | +1.48 | +0.98 |
| 2024 | Oct | +0.75 | +0.89 | +0.60 | +0.63 | +1.89 | +0.81 | +1.09 |
| 2024 | Nov | +0.64 | +0.87 | +0.40 | +0.53 | +1.11 | +0.79 | +1.00 |
| 2024 | Dec | +0.61 | +0.75 | +0.47 | +0.52 | +1.41 | +1.12 | +1.54 |
| 2025 | Jan | +0.45 | +0.70 | +0.21 | +0.24 | -1.07 | +0.74 | +0.48 |
| 2025 | Feb | +0.50 | +0.55 | +0.45 | +0.26 | +1.03 | +2.10 | +0.87 |
| 2025 | Mar | +0.57 | +0.73 | +0.41 | +0.40 | +1.24 | +1.23 | +1.20 |
| 2025 | Apr | +0.61 | +0.76 | +0.46 | +0.36 | +0.81 | +0.85 | +1.21 |
| 2025 | May | +0.50 | +0.45 | +0.55 | +0.30 | +0.15 | +0.75 | +0.98 |
| 2025 | June | +0.48 | +0.48 | +0.47 | +0.30 | +0.80 | +0.05 | +0.39 |
| 2025 | July | +0.36 | +0.49 | +0.23 | +0.45 | +0.32 | +0.40 | +0.53 |
| 2025 | Aug | +0.39 | +0.39 | +0.39 | +0.16 | -0.06 | +0.82 | +0.11 |
| 2025 | Sep | +0.53 | +0.56 | +0.49 | +0.35 | +0.38 | +0.77 | +0.30 |
| 2025 | Oct | +0.53 | +0.52 | +0.55 | +0.24 | +1.12 | +1.42 | +1.67 |
| 2025 | Nov | +0.43 | +0.59 | +0.27 | +0.24 | +1.32 | +0.78 | +0.36 |
| 2026 | Dec | +0.30 | +0.45 | +0.15 | +0.19 | +2.10 | +0.32 | +0.38 |
The full UAH Global Temperature Report, along with the LT global gridpoint anomaly map for December, 2025 as well as a global map of the 2025 anomalies and a more detailed analysis by John Christy, should be available within the next several days here.
The monthly anomalies for various regions for the four deep layers we monitor from satellites will be available in the next several days at the following locations:
Only the 6th warmest December
1 2023 0.74
2 2024 0.61
3 2019 0.43
4 2015 0.35
5 2017 0.31
6 2025 0.30
7 2003 0.26
8 1987 0.25
9 2021 0.22
10 2016 0.16
Interesting that 1987 was so warm.
This is the first time since May 2023 that the anomaly has been below the current trend line.
The anomaly for the USA is very high. Second warmest anomaly for any month, and the warmest December.
Bellman
” The anomaly for the USA is very high. ”
Although the CFS V2 forecast for the US in January only includes land data, it can still be a meaningful hint to the previous December:
https://www.cpc.ncep.noaa.gov/products/CFSv2/imagesInd3/usT2mMonInd1.gif
A comparison with the forecast for Europe is interesting:
https://www.cpc.ncep.noaa.gov/products/CFSv2/imagesInd3/euT2mMonInd1.gif
Maybe it’s better to save them.
US
https://i.postimg.cc/SK0GX1fL/us-T2m-Mon-Ind1-050126.png
EUR
https://i.postimg.cc/qvKsdXHp/eu-T2m-Mon-Ind1-050126.png
Was 1998 warmer than 2020? I can’t tell what year is in 4th place behind 2016.
Greyhound81
I just had a look at a descending sort of the yearly averaging of UAH’s monthly LT data since Jan 1979:
2024 0.774 (C)
2025 0.472
2023 0.431
2016 0.389
2020 0.351
1998 0.348
2019 0.296
2017 0.265
2010 0.193
2022 0.148
*
You may mean the 5th place in between…
The 1877 spike continues to serve as a template. I wasn’t sure if the tail would be longer this time given the origin of the spike is different.
https://localartist.org/media/HTvAkjsaENSO2512.png
I’ve nearly finished a paper explaining why climate largely repeats after 3560 years. I hope to make it public in January.
https://localartist.org/media/NGRIPCores3500shift.png
Dr. Spencer, let me know if you’d like to see a draft copy.
I posted this comment last month, and now I see that the linked graphs have been viewed over 100 times.
I’ll re-up the graphs https://ibb.co/chfy3mmq and the accompanying follow up post for the benefit of any new lurkers.
Ark, why do you keep avoiding the issue?
https://www.drroyspencer.com/2025/12/uah-v6-1-global-temperature-update-for-november-2025-0-43-deg-c/#comment-1726504
Today’s entry notes that December, 2025 was +0.30 deg. C departure from the 1991-2020 mean. However, the earliest mean, covering the first 20 years of observations (1978-1999) was about 0.22 lower than the current, meaning the departures you report appear smaller because of the use of a later baseline average–otherwise Dec. 2025’s anomaly would be something like .52 Deg C.
Why raise the baseline other than to reduce the apparent anomaly?
MFA
” Why raise the baseline other than to reduce the apparent anomaly? ”
This was not the reason, even if many of those I name the pseudo-skeptics would welcome it.
The reason to the change of the reference period, first from 1979-1998 to 1981-2010 and then from 1981-2010 to 1991-2020 is manifestly the will to be in agreement with WMO’s respectively newest recommendation.
Some follow it too, e.g. JMA, the Japanese Met Agency.
Others don’t, especially NASA GISS (1951-1980), RSS (still on 1979-1998) or partly NOAA which for global time series keeps on 1901-2000.
My guess (!): this might be due to how these climate data providers construct anomalies out of historical data; the probably tend to keep as reference the period with the most available absolute data, what reduces the standard deviations and gives thus better estimates.
But it downplays and therefore misrepresents the amount and rate of change.
To remain honest, Dr. Spencer should display the original baseline as well as the later one.
In a few months we may start to see negative anomalies.
Sure, Jan. But if so, not for long.
https://youtu.be/l2QjDA9QgNE
20 years ago 60 Minutes ran a segment titled Rewriting the Science, in which James Hansen spoke out about White House censorship of climate science.
The amount of CO2 in the air then was ~382ppm; it’s now ~428ppm.
So it will take 186 years to double CO2…which would give us perhaps less than 1°C. So need to worry, then.
I don’t know where I’ll be then, but I sure as hell won’t smell too good.
No, it won’t take that long, because the rate of CO2 increase is accelerating.
https://gml.noaa.gov/ccgg/trends/
Try to keep up.
So…what caused the 2024 spike in the LT? If it was CO2, why wasn’t it sustained?
These spikes are frequent throughout the holocene and in the instrument record in the late 19th century, mid 20th century, and 1980-2024.
They are in time with the motions of Jupiter and Saturn operating on a 60 year pattern.
Insolation models used by NASA decades ago built the idea of longer term variations by retained heat from variations in the motions of Jupiter and Saturn leading to the idea of perhaps a linear 100,000 year cycle via the retention of heat in snow and ice and the resulting albedo effects of advances and retreats of glaciers. This brings us to longer termed cycles of the planets.
These effects are variously thought to also build up over time into a 100,000 year linear effect on earth’s eccentricity. But this is more science community myth than anything available in print as what is in print suggests strongly otherwise.
The pattern lines up with 20 and 60 year period motions of Jupiter and Saturn. This creates the major spikes and stepped warming noted in the instrument record. The physics is based on the gravitational influence on variations in earth’s speed in its annual orbit. Through half of earth’s orbit this influence changes the time earth spends in its orbit furthest and closest to the sun. Each ~450 years it moves from a warming influence to a cooling influence as it takes 900 years for jupiter and saturn close encounters to cover the entire celestial compass.
So for ~450 years earth’s travel closest to the sun move 1/2 an orbit more slowly and then the next ~450 years it moves faster. These are only approximate because the outer gas giants have an influence on the timing on longer term orbits and there may be yet to be identified space objects beyond Neptune that cause other perturbations that are too distant or too distributed to be observed regularly because they emit nor reflect significant light.
These forces create the major bumps in the temperature record that some have attributed to AMO and PDO variations in temperature that are seen in the instrument records.
In addition to the combined motions of jupiter and Saturn (20 year pattern of conjunctions each occurring about 240 degrees apart meaning over 60 year period they will line up once or twice in one half of the orbit with that pattern which half gets 2 varying once every ~450 years in a 900 year cycle. These variations created the larger bumps seen in the ice core records, like the MWP period, Roman Optimum, and the Minoan Warm Period. Likewise between the MWP and the present its responsible for the LIA.
The combined motions of Uranus and Neptune besides influencing the 60 year pattern and 900 year pattern of Jupiter and Saturn, moves slowly around the heavens over an approximate 170 year cycle via the close 2:1 orbit ratio between those two major gas giants. The effect is very small but it lasts a long time creating short term effects of ~80+years and 170+ years (also creating the conditions for the Voyager expeditions using planet gravity to cover vast distances in space for those space vehicles that NASA says occurs about once every 175 years)
It is also believed that axial motions of earth while not influencing the mean annual insolation received by earth, influences how much of that is reflected from variations in snow and ice cover.
CO2 may have some effect in that the recent peak is a good deal warmer than late 19th century effect. And in the 1940’s peak Uranus was in opposition to Neptune having a cancelling effect. But effects if CO2 still needs sorting out from these longer termed natural cycles.
Thanks for that. I feel that there are many planetary effects (on Earth) that we have yet to discover.
To what do you attribute the 45 year drop in global cloud cover (which coincides with the modern warming period)? Do you believe it is cosmic rays or, I read only yesterday, yet another effect from CO2? However, even many proponents of this theory say that the level of CO2 would have to be very high to affect cloud formation.
Because CO2 has absolutely nothing to do with it. !
Why should such a short, sudden increase be attributed to any source identified as having rather long-term effects?
Buzz,
There’s a nice article by Zeke Hausfather looking at attribution of 2024 exceptionally high temperature anomaly here:
https://www.carbonbrief.org/analysis-what-are-the-causes-of-recent-record-high-global-temperatures/
The summary attribution is shown in this figure from that article:
https://www.carbonbrief.org/wp-content/uploads/2025/12/recent-warming-7.png
I am going to take a wild guess that whatever effect raised the temperature so dramatically in early 2023 has now changed. Was it the Hunga-Tonga effect?
I thought that Dr Spencer attributed it to be Hunga Tonga a couple of years ago, but he now states that there was no such effect. Bill Hunter’s is plausible.
SOLAR MINIMUM UPDATE
It’s the most magical time of the year — when estimates of last year’s global average temperature anomaly come out. Time to dust off my “last year was hot” auto-response.
https://bsky.app/profile/andrewdessler.com/post/3l7yxx4mc4b2h
According to MEI (Multivariate ENSO Index)
https://psl.noaa.gov/enso/mei/data/meiv2.data
the UAH-LT anomalies could remain low for some time due to the time lag between ENSO signals (here: La Niña) and their appearance in the LT data.
However, La Niña will not last longer if the prediction nino3+4 is correct:
https://www.cpc.ncep.noaa.gov/products/CFSv2/imagesInd3/nino34Mon.gif
Do you think the record from 2024 will be broken before the end of the decade?
¡No sé!