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Mika Rantanen @mikarantane.bsky.social · 35m

Isaias on Atlantin ensimmäinen hurrikaani tänä syksynä - myöhäisin ensimmäinen hurrikaani koko satelliittiaikakaudella. Isoin syy El Niño, joka lisää tuulisuutta Atlantilla ja siten vaikeuttaa hurrikaanien kehittymistä.

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Mika Rantanen @mikarantane.bsky.social · 59m

Yes! Good question. This is how the correlation map looks like for Jan-Sep. However, this gives equal weight for summer months when there are very few storms. I should probably calculate similar map for ONDJFM. Like NAO pattern, but shifted eastwards.

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Mika Rantanen @mikarantane.bsky.social · 18h

Number of windstorms, or days with stormy winds (21 m/s), has been unusually low in Finland this year. Jan-Sep period gave only 5 storm days, which is the 2nd lowest number since 2006 when the reporting period starts. More in @suomenluonto.bsky.social (in Finnish): suomenluonto.fi/myrskyjen-ma...

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Mika Rantanen @mikarantane.bsky.social · 18h

En tiedä, en ole ainakaan huomannut yhtään uutista.

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Mika Rantanen @mikarantane.bsky.social · 23h

Ylen jutussa yle.fi/a/74-20249365 oli @ilmatieteenlaitos.fi eli meidän tekemä helle-ennuste vuodelle 2040. Esimerkkinä oli 17.7.2018 hellepäivä, joka simuloitiin Climate DT storyline-ajolla +2 asteen ilmastossa. Simulaation perusteella sama säätilanne olisi vuonna 2040 noin 1,8 °C lämpimämpi.

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Mika Rantanen @mikarantane.bsky.social · 23h

En ole varma talvien lämpötiloista, mutta ainakin kesien lämpötilat Lapissa ovat ylittäneet keskiajan lämpötilat. www.nature.com/articles/s41... ja www.nature.com/articles/s41...

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Mika Rantanen @mikarantane.bsky.social · 06/10/2026

Joo, ilmastojärjestelmän luontaisesta vaihtelusta, esim. El Nino-vaihtelu. Vuosi 2025 oli sinänsä "normaali" että lämpötila oli lähellä odotettua. Sen sijaan esim. 2024 oli voimakas lämpöpiikki joten luontaisen vaihtelun osuus sen vuoden lämpötiloista oli suurempi (0.15 °C).

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Mika Rantanen @mikarantane.bsky.social · 06/10/2026

Suomen Ilmastopaneeli @ilmastopaneeli.fi julkaisi tänään raportin "Ilmastonmuutoksen tilannekuva 2026 – Miten ilmastonmuutos etenee ja vaikuttaa Suomessa ja globaalisti" ilmastopaneeli.fi/hae-julkaisu... Suomi on lämmennyt jo noin 2,5 astetta esiteollisesta ajasta.

Raportin kuva 1. Aikasarja Suomen ja maapallon keskilämpötilan kehityksestä vuosina 1900-2025, sekä ennusteet vuoteen 2050 asti.

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Reposted by Mika Rantanen

Ilmatieteen laitos - Finnish Meteorological Institute @ilmatieteenlaitos.fi · 06/10/2026

Vuonna 2024 Jari-myrskyn yhteydessä havaittiin Perämerellä poikkeuksellisen alhaisia vedenkorkeuksia. Tutkijat selvittivät, mistä ennätyksellisen alhaiset vedenkorkeudet johtuivat. Lue lisää uutisesta👇 www.ilmatieteenlaitos.fi/uutinen/6ZEj...

ilmatieteenlaitos.fi

Tutkimus: Jari-myrsky aiheutti Perämerelle ennätyksellisen alhaisen

Merivesi laski poikkeuksellisen alhaiseksi Perämerellä marraskuussa 2024, minkä vuoksi esimerkiksi lauttaliikenne Hailuotoon jouduttiin hetkellisesti keskeyttämään. Tutkijat selvittivät, mistä

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Mika Rantanen @mikarantane.bsky.social · 30/09/2026

The median of Niño 3.4 forecasts for September is ~3.3 °C and for October ~3.7 °C. While the warming so far has beaten most forecasts, now it seems that for the first time the situation may be the other way round.

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Mika Rantanen @mikarantane.bsky.social · 30/09/2026

The 10th Copernicus Ocean State Report (OSR10) was published today: marine.copernicus.eu/news/publica... In the report, we have a paper on record-low sea levels in the Bothnian Bay in Nov 2024, caused by an extreme windstorm event (Storm Jari). Open-access paper: sp.copernicus.org/articles/7-o...

sp.copernicus.org

Record low sea levels in the Bothnian Bay in November 2024

Abstract. On 21 November 2024, there was an extreme event within the Bothnian Bay, a sub-basin of the Baltic Sea, when a record low sea level of −153 cm was measured at Kemi, at the northern end of th...

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Mika Rantanen @mikarantane.bsky.social · 28/09/2026

Do you remember the drought affecting Finland that received a lot of media attention? In early May, cumulative precipitation was record-low in Finland. Turns out that the summer and September were quite wet, and cumulative precipitation in Finland is now actually above average!

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Mika Rantanen @mikarantane.bsky.social · 25/09/2026

They do, but the radar images are often filtered to show only rainfall. Those unfiltered radar data are not typically shown in public weather service webpages. Because, you know, birds and insects are "garbage" for meteorologists 😀

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Mika Rantanen @mikarantane.bsky.social · 25/09/2026

It was totally clear weather, no rain at all. (Fair weather is typically needed for crane migration as they utilise rising air motions in their way)

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Mika Rantanen @mikarantane.bsky.social · 25/09/2026

New paper by @daanvandenbroek.com and me just published in @rmets.org Weather: "The 2026 cold wave brought northern Fennoscandia its coldest 2-week period since 1987" rmets.onlinelibrary.wiley.com/doi/10.1002/... Check out the brilliant thread by Daan below 👇

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Mika Rantanen @mikarantane.bsky.social · 25/09/2026

No, the arrow points to the line of birds. They are flying to SSW. Other blue radar signatures are probably insects.

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Mika Rantanen @mikarantane.bsky.social · 24/09/2026

Radar image of Tuesday's mass crane migration. A 100 km long line of migrating cranes was clearly visible on weather radar. It is estimated that around 10,000 (?) cranes were involved in that formation. The highest count observed was 26,000 migrating cranes on that day in Kangasala (near Tampere).

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Julia Kemppinen @juliakemppinen.bsky.social · 23/09/2026

Just accepted! Our study led by @mikarantane.bsky.social in Theoretical and Applied Climatology shows the spatial heterogeneity in growing season dynamics across northern environments 🍃🌡️🥵 While waiting for the final publication, you can check out our preprint version: doi.org/10.21203/rs....

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Reposted by Mika Rantanen

Lukas Brunner @lukasbrunner.bsky.social · 21/09/2026

🚨New publication How does internal climate variability affect the calculation of the ETCCDI temperature and precipitation extreme indices? In our paper, we introduce the Variability Atlas, a flexible toolset to address this question for users of all experience levels! doi.org/10.1088/1748...

doi.org

The variability atlas: how internal climate variability affects the estimation of climate extreme indices

The variability atlas: how internal climate variability affects the estimation of climate extreme indices, Brunner, Lukas, Mithal, Vidur, Borchert, Leonard F, Sillmann, Jana, Poschlod, Benjamin

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Mika Rantanen @mikarantane.bsky.social · 18/09/2026

Unfortunately no! I only have the 2-m temperature data since 1979.

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Mika Rantanen @mikarantane.bsky.social · 18/09/2026

Composites of winter (DJF) temperature anomalies of moderate-to-strong ENSO events (RONI threshold ±1.0 °C) in Europe. Note, these are detrended temperature anomalies. The pattern is cold for northeastern Europe but closer inspection reveals that two winters (1987 and 2010) push the average down.

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Mika Rantanen @mikarantane.bsky.social · 17/09/2026

El Niñon voimakkuus saavutti tiistaina kolmen asteen rajan, Ilmatieteen laitoksen tutkija Mika Rantanen sanoo. "El Niño voimakkaasti lämmenneessä ilmastossa on yhdistelmä, jota ei ole koskaan aikaisemmin koettu." www.is.fi/kotimaa/art-...

is.fi

Näin super-El Niño -ilmiö voi näkyä Suomessa

El Niño saavuttaa huippunsa marras-joulukuussa. Ilmiön vaikutukset näkyvät pitkälle ensi kevääseen saakka.

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Mika Rantanen @mikarantane.bsky.social · 16/09/2026

Kollega A-J Punkka on tässä oikeassa - harvoin syyskuussa tehdyssä kausiennusteessa on niin selkeä signaali talvikaudelle. Selvästikin malleissa on jokin driveri, (El Niño?), mikä työntää niitä samaan asentoon. Tuleva talvi on El Niñon kaukovaikutusten "stressitesti"? yle.fi/a/74-20246396

yle.fi

Meteorologi: ”Harvoin näkee näin voimakkaita signaaleja” – talvesta on tulossa talvinen

Mikäli kausiennuste toteutuu, vesisateet pysyvät loitolla ja Suomessa saadaan nauttia todennäköisesti talvisista olosuhteista ensi talvena.

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Mika Rantanen @mikarantane.bsky.social · 16/09/2026

El Niño strengthening into unseen territory. The Niño3.4 region just reached a +3.0 °C anomaly (relative to the 1991–2020). Such a warmth has never been observed in September, and it's only a few hundredths of a degree away from the 2015 all-time record.

Nino3.4 temperature anomaly in different years. The values in 2026 are above the previous years' temperatures and close to 2015 all-time record.

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Mika Rantanen @mikarantane.bsky.social · 14/09/2026

Classic El Niño signal is visible in the latest C3S seasonal forecasts for the upcoming winter. The multi-model mean MSLP anomaly is almost a carbon copy of El Niño composite for the Jan-Feb period. confluence.ecmwf.int/spaces/CKB/p...

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Reposted by Mika Rantanen

Mika Rantanen @mikarantane.bsky.social · 11/09/2026

Job alert: full professorship in meteorology in the University of Helsinki! New position in dynamic meteorology, synoptic-scale meteorology and numerical weather prediction. The vacancy has been opened due to the passing of Dr. Victoria Sinclair. Details: jobs.helsinki.fi/job/Helsinki...

jobs.helsinki.fi

Professor/Associate or Assistant Professor, Meteorology

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Mika Rantanen @mikarantane.bsky.social · 14/09/2026

Melko voimakas lintujen aamumuutto käynnissä selkeällä taivaalla. Lähinnä hyönteissyöjiä kuten kuten västäräkkejä ja rautiaisia poistuu Suomesta.

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Reposted by Mika Rantanen

Simon Lee @simonleewx.com · 10/09/2026

8 years ago, I tweeted side-by-side maps from NASA GISS showing global temperatures in 1976 and 2018 – both hot summers in the UK. It subsequently went viral and was printed in the Daily Mail! The 2026 version is stark. Two locally extreme summers separated by 50 years of global climate change.

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Mika Rantanen @mikarantane.bsky.social · 11/09/2026

jobs.helsinki.fi

Professor/Associate or Assistant Professor, Meteorology

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Mika Rantanen @mikarantane.bsky.social · 11/09/2026

"Oletan, että ennätys rikkoutuu lähipäivinä. Sitten olemme ennennäkemättömissä lukemissa" Nino3.4 alue jatkanut lämpenemistään pienen tauon jälkeen. Lämpötila on nyt 2,9 °C tavanomaista korkeampi, kun vuoden 2015 El Niñossa tehty ennätys on 3,1 astetta. yle.fi/a/74-20245194

yle.fi

Tyynellä valtamerellä syntyvä El Niño voi rikkoa tällä kertaa kaikkien aikojen ennätyksen

Maailman säitä myllertävä El Niño vahvistuu loppuvuoteen asti. Suomessa se voi nostaa suklaan ja kahvin hintaa.

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Reposted by Mika Rantanen

Prof Ian Hall @ianhall.bsky.social · 08/09/2026

Climate change increases deadly heat risk in Southern Europe. Across 34 countries, 2022-like heat mortality events were 26.5× more likely in Southern Europe than under pre-industrial conditions, ~10× the European average. Risk rises sharply with warming. www.nature.com/articles/s44...

nature.com

Extreme event attribution for heat-related mortality due to anthropogenic climate change across Europe - Nature Health

A method combining extreme event attribution with epidemiological models shows that extreme heat-related mortality events in Southern Europe are 26.5 times more likely than in pre-industrial times, wi...

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Mika Rantanen @mikarantane.bsky.social · 09/09/2026

Does anyone have a read-only link to this paper? Thanks!

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Reposted by Mika Rantanen

Rick Thoman @alaskawx.bsky.social · 06/09/2026

The #Arctic (land & seas poleward north of 60ºN) finished up with the warmest summer on record in ERA5 data from @copernicusecmwf.bsky.social. The five warmest summers all since 2016. However, within 1100km (700 miles) of the North Pole (80° to 90°N) this was the coolest summer since 2014. #Climate

Time series graphic plotting the June through August average temperature in the Arctic each year 1950 to 2026. The five highest and lowest values are highlighted, and an estimate of the time varying average is also shown.

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Mika Rantanen @mikarantane.bsky.social · 04/09/2026

Summers are warming so fast in the UK that scientists can’t keep track. Abstract of a new study: “Summer 2025 was the warmest so far recorded for the UK” The paper was published today, and indeed, that "so far" was a useful addition. rmets.onlinelibrary.wiley.com/doi/10.1002/...

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Reposted by Mika Rantanen

Met Office - weather and climate @metoffice.gov.uk · 01/09/2026

Summer 2026 is provisionally the UK’s warmest summer on record with the season’s mean temperature made around 130 times more likely due to human-induced climate change. Here, we delve into the numbers 🧵

Mean temperature for 2026 in the UK. The map shows widely above average temperature, particularly in the south.

Rainfall amounts in summer 2026 in the UK compared to average. The maps shows widely dry conditions, though the west of Scotland is slightly wetter than average

Sunshine duration in summer 2026 compared to average. The map shows widely sunny conditions in the season, with the south of the country particularly sunny.

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Mika Rantanen @mikarantane.bsky.social · 01/09/2026

Happy autumn! Summer 2026 in Finland was very close to the 1991–2020 averages, and even slightly above it. It may feel counterintuitive, but I'd argue it's part of the shifting baseline -syndrome. We just didn't have those week-long heatwaves this year, as opposed to western Europe.

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KarSteN Haustein @khaustein.bsky.social · 31/08/2026

Globally, the hottest August in observed history is just about to end. In Western Europe, the summer of 2026 (June, July, August) has been the warmest as well. Compared to this year, 1976 (the famous UK summer) and 2003 (the hottest EU summer so far) look like amateurs in terms of heat (1/2)

Global map of temperature departures with most continental regions as well as the tropical Pacific in red (hot). Parts of Antarctica in blue (cold)

Source: http://www.karstenhaustein.com/climate

Map of Europe with blue and cold patches for cold and hot temperature departures from the long-term climate average (1961-1990). France and the UK in red. All else rather blue.

Map of Europe with blue and cold patches for cold and hot temperature departures from the long-term climate average (1961-1990). All of central Europe in red. Parts of the Atlantic in blue

Map of Europe with blue and cold patches for cold and hot temperature departures from the long-term climate average (1961-1990). All of central and Southern Europe in red. No blue left anymore.

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Mika Rantanen @mikarantane.bsky.social · 28/08/2026

Exceptionally cold morning in eastern Lapland with minimum temperature down to -6.6 °C in Savukoski Tulppio. This is the coldest August temperature observed in Finland since 1986, and it ties the -6.6 °C reading from August 1989.

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Reposted by Mika Rantanen

Erich Fischer @erichfischer.bsky.social · 27/08/2026

Children disproportionately affected by heat Our new Science Advances paper, led by @rosapietroiusti.bsky.social and @wimthiery.eu, shows that children today – and in the future – are disproportionately affected by heat stress. www.science.org/doi/10.1126/...

science.org

Age-specific exposure to human-induced increases in humid heat

Children are particularly vulnerable to climate change impacts and will face intensifying effects of climate change during their lifetimes. Here, we show that children already face disproportionate ex...

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Mika Rantanen @mikarantane.bsky.social · 26/08/2026

As a side note, apparently it was hard to find reviewers for such a specific topic in this paper - it took 603 days from submission to acceptance. Of this, 32 days for revisions so the net review time was 571 days (!).

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Mika Rantanen @mikarantane.bsky.social · 25/08/2026

Yes, when looking at point-wise, your analysis looks correct. However mine considers the same period (MJJ) from both ENSO and temperatures, while yours looks to take the ENSO from the entire previous year.

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Mika Rantanen @mikarantane.bsky.social · 25/08/2026

Somewhat similar pattern is also evident in MJJ 2026, although the ridges in W-Eur and Siberia were stronger than anticipated based on the correlations. Also, the trough in the subtropical North Pacific is missing in 2026, maybe that could be one factor that has influenced downstream in Europe.

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Mika Rantanen @mikarantane.bsky.social · 25/08/2026

Great questions, less answers. I agree that it could be also that the temperatures were "right but for wrong reasons". FWIW, I quickly looked at the situation at 500-hPa geopotential height. Some sort of a Rossby wave train is present in the correlation map, originating from the Pacific (?)

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Mika Rantanen @mikarantane.bsky.social · 25/08/2026

How much of the May–July 2026 temperatures in Europe was related to El Niño? Here's comparison of 1979–2025 correlation map and detrended temperatures for MJJ 2026. Not a perfect match, but not bad either. Especially the east-west gradient across Europe is consistent with the El Niño pattern.

A map showing the correlation coefficient between CPC relative ONI index and 2-m temperatures for MJJ 1979–2025. Weak positive correlation in western Europe and stronger negative correlation in eastern Europe.

Detrended temperature anomaly for MJJ 2026. Hot in western Europe and cooler in eastern Europe.

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