The highlight of this week was meeting with @mattpriestley.bsky.social here in Helsinki and his seminar about constraining future windstorm trends for Europe. Very interesting work!

Blocking high in action. The newest ECMWF forecast keeps Finland completely dry for the next 10 days.

That is a prominent signal for blocking predicted by ECMWF for the rest of the month. It will likely lock in a record-warm September for much of Fennoscandia, the third year in a row.

Windy day ahead tomorrow. One major factor is the powerful jet stream that facilitates cyclogenesis. Not so often we'll have 90 m/s wind speeds above us.

September has started off record-warm in about half of the country. And where it has not been the warmest, the record is from September 2024.

Another warm night in northern Finland. Sodankylä and basically the whole Lapland has not yet seen frost in September. Sodankylä's lowest temperature so far is 4.2 °C - remarkably high for September.

Lämmin syyskuun alku näkyy myös vesistöissä, kuten YLE uutisoi pari päivää sitten (yle.fi/a/74-20182391). Päijänteen pintalämpötila nousi yli kolme astetta syyskuun alussa ja on tällä hetkellä lähellä ajankohdan ennätyksiä (jotka tehtiin viime vuonna).

Huikean lämmin syyskuun alku, jälleen kerran. Suomen keskilämpötila 1.–13.9. oli 15,0 astetta, joka on vain 0,1 astetta vuoden 2024 ennätystä alempana. Vuoden 2023 syyskuun alku tulee kolmantena. @suomenluonto.bsky.social-blogissa vähän pidemmästi: suomenluonto.fi/huikean-lamm...

What a warm day. Exceptionally high temperatures almost in the whole country. By 16:00 local time, the highest temperature was 24.8 °C in Kokemäki Tulkkila. The reading is also new national daily heat record for this date.

Hot off the press: We can provide for the first time a systematic attribution of recent #heatwaves to the emissions of #carbon_majors. Essential new #Nature article coordinated by @yannquilcaille.bsky.social at @ethz.ch, with numerous contributors @usyseth.bsky.social: www.nature.com/articles/s41...

🚨 Important paper in Nature: "Systematic attribution of heatwaves to the emissions of carbon majors". www.nature.com/articles/s41...

There are five post-doctoral positions open in FMI @ilmatieteenlaitos.fi. One of them will be situated in our unit, and the topic is about convective storms and severe extreme weather events. Deadline for applications 25.9.2025. valtiolle.fi/en/jobs/post...

An intense back-building thunderstorm has been present over central Finland during the morning hours. The storm develops upwind, making it appear stationary. As a result, Jyväskylä airport has received > 60 mm of rain in just a few hours.

New from @copernicusecmwf.bsky.social: August 2025 in Europe was "only" 12th warmest on record and noticeably cooler than the last three Augusts which rank as the top-3. Regardless, August is Europe’s 2nd fastest-warming month in the past 50 years with a trend of 0.58 °C / decade.

As @extremetemps.bsky.social noted, the daily minimum temperatures today in Finland were in many places record-high for September. In Sodankylä Tähtelä the minimum of 14.4 °C ties the monthly record, set just in last year.

25.8 °C today in Salo Kärkkä marks the third hot day of September 2025. For the first time on record, September has now had more hot days (3) than June (2). [Hot day: maximum temperature > 25.0 °C somewhere in Finland]

I had an engagement with blogger, failed California gubernatorial candidate, and self-identified reporter Michael Shellenberger this past week, which started out being about this new paper being heralded by climate skeptics as disproving global sea-level acceleration. (LONG 🧵)

There has been strong night-time bird migration in recent nights, for example last night. The new radar-based tool has revealed that birds can reach heights of almost 4 km (!) over southern Finland. ilmu.fmi.fi/realtime

With a mean temperature of 14.8 °C, summer 2025 in Finland was the coolest in the 2020s. However, if it felt cool(ish), that’s only because the previous five summers have been very hot. It’s been a while since we had a genuinely cold summer, like in 2017.

🌊 In 2023, the ocean carbon sink weakened for the first time in a record-hot year 🌡️🌎 Our new study in Nature Climate Change quantifies this unexpected decline and explains how it came about. 👇 doi.org/10.1038/s415...

New analysis from @metoffice.gov.uk showing that the record-breaking hot UK summer of 2025 has been made much more likely by human-induced climate change and such a hot summer would be expected about once every 5 years in current climate. www.metoffice.gov.uk/about-us/new...

This is not normal. Japan is continuing its run of astonishing temperature records. The country has just had its hottest summer for the third year in a row, and by a substantial margin. Data: JMA

September starts warm in Fennoscandia. ECMWF subseasonal forecast indicates that the warmth will persist for at least 2-3 weeks. Last two Septembers (2023 & 2024) were unprecedentedly warm in Finland - interesting to see if the trend continues.

Summer 2025 in Sodankylä, Finland was the coolest summer of the 2020s, but still ~0.5 °C warmer than the most recent 30-year period (1996–2025). Modern summers in northern Fennoscandia are warmer than those in medieval times: www.nature.com/articles/s41... & www.nature.com/articles/s41...

Summer 2025 in Finland in short: cool, hot, cool. Not many of the past summers have been as clearly divided into three parts as this one.

Kuuman ja kostean heinäkuun helleaallon jälkeen elokuun loppupuoli on kääntymässä poikkeuksellisen viileäksi. Alustavien arvioiden perusteella 16.–31.8. voi Helsingissä olla jopa 2000-luvun kylmin vastaava jakso. Lue @mikarantane.bsky.social bloggaus Suomen Luonnon sivuilta.

2000-luvun kylmin elokuun loppupuolisko Etelä-Suomeen? Siltä se näyttää. Esimerkiksi Helsingin Kaisaniemen keskilämpötila 16.–31.8. jäämässä noin 14,2 asteeseen, joka olisi kylmin vuoden 1998 jälkeen. suomenluonto.fi/etela-suomes... @suomenluonto.bsky.social

Post-tropical cyclone Erin over the North Atlantic today. Erin is no longer tropical cyclone but has transitioned to a large extratropical cyclone - luckily its post-tropical intensification occurs over the ocean. MTG satellite image from @eumetsat.int: view.eumetsat.int/productviewe...

Numerical weather prediction models (ECMWF IFS) still outperform AI weather models in forecasting record-breaking hot and cold extremes and unseen wind extremes Preprint arxiv.org/abs/2508.15724 with Zhongwei Zhang @erichfischer.bsky.social @zscheischlerjak.bsky.social and Sebastian Engelke

Only +3 °C at Helsinki Vantaa airport this morning. Quite a cold for August, and in fact the coldest August morning at the airport since 1997! Even freezing temperatures central / northern parts of the country.

Our recent paper @natgeosci.nature.com shows that over the Med, marine heatwaves are linked to subtropical ridges rather than atmospheric blocking, the typical cause of atmospheric heatwaves in central Europe. The brilliant ECRs Giulia Bonino and Ronan McAdam led this work! 🌊Link in the comments.

Summer 2024 featured unprecedented warmth in the European Arctic, causing melting of 1 % of the total ice volume on Svalbard. Bad news is that in 2100 and even in the optimistic SSP1-2.6 emission scenario, 50% of the future summers will be warmer than 2024. www.pnas.org/doi/10.1073/...

Our latest research investigates the remarkable heatwave that affected part of the Arctic in the summer of 2024. It caused a 1 percent loss in Svalbard's ice, making this region one of the most significant contributors to global sea-level rise last year www.pnas.org/doi/10.1073/...

Great to present our recent study on the record-warm summer of 2024 in Svalbard ❄️🔥, right in the climate change hotspot of Longyearbyen itself. A full audience and great discussion afterwards at UNIS. On Tuesday I’ll be giving a lecture to students of the Polar Meteorology and Climatology course.

Very sharp cold front will arrive in the west coast of Finland tonight. The front is associated with wind gusts of > 20 m/s, heavy rainfall and possibly lightning.

In July Fennoscandia was hit by a heatwave similar to one that hit the region in 2018. In just seven years, similar events have become almost twice as likely due to increased global temperatures from 1.1 to 1.3°C. Every fraction of a degree matters! www.worldweatherattribution.org/intense-two-...

Heinäkuun 12.–25. päivänä koettu kahden viikon hellejakso Norjassa, Ruotsissa ja Suomessa oli ilmastonmuutoksen vuoksi noin kaksi astetta kuumempi ja vähintään kymmenen kertaa todennäköisempi kuin ilman ihmisten aiheuttamaa ilmaston lämpenemistä. www.ilmatieteenlaitos.fi/tiedote/2Vb9...

Ilmastonmuutos teki heinäkuun helleaallosta noin kaksi astetta kuumemman ja vähintään kymmenen kertaa todennäköisemmän kuin ilman sitä, uusi kansainvälinen tutkimus kertoo. yle.fi/a/74-20177256

World weather attribution rapid study on the two-week Fennoscandian heatwave is out. The key results do not surprise: 1) the heatwave was ∼2 °C hotter and 2) at least 10 times more likely due to climate change. www.worldweatherattribution.org/intense-two-...

Tropical nights are becoming clearly more frequent in Helsinki, Finland. This summer we have had four nights with a minimum temperature above 20°C. Observations from Helsinki Kaisaniemi show a clear uptick in the occurrence of tropical nights during the 21st century.

1) 🔥 New research in Earth’s Future! We show that AI weather prediction models, combined with climate simulations, can be used to estimate the influence of human-made climate change on heatwaves. 👉 tinyurl.com/a5b5ndby @csic.es @igeociencias.bsky.social #ClimateChange #AI #Heatwaves

Kansainvälinen tutkimus osoittaa, että Kiinan pienhiukkaspäästöjen raju väheneminen on tärkein syy ilmaston lämpenemisen kiihtymiselle vuoden 2010 jälkeen. www.ilmatieteenlaitos.fi/tiedote/4Pca...

Orange sun yesterday in southern Finland due to smoke from Canadian wildfires.

Fennoskandian helleaalto oli heinäkuussa merkittävin säätapahtuma Euroopassa. Suomessa helleaalto oli poikkeuksellinen erityisesti kestoltaan, eikä niinkään ylimmiltä lämpötiloiltaan. Mediatiedotteemme aiheesta: www.ilmatieteenlaitos.fi/tiedote/6uTT...

This is unbelievable. The high temperature at one of Finland’s northernmost weather stations, in the municipality of Sodankylä (Lapland region) within the Arctic Circle at latitude 67.3°N, reached at least 25°C for 26 days in a row. Records date back to 1908.

"Analysis of ensemble members that simulate analogs of the observed pause indicates that the current slowdown could plausibly persist another 5 to 10 years" England et al. (2025): Minimal Arctic Sea Ice Loss in the Last 20 Years, Consistent With Internal Climate Variability doi.org/10.1029/2025...

Tässä jo aiemmin kesäkuussa ilmestynyt mielipidekirjoituksemme Lapin Kansassa. Juttu päättyy sanoihin "Mutta se tiedetään, että edessä on vielä monta kertaa pitkä kuuma kesä." Ja siitähän ei mennyt kuin reilu pari viikkoa kun ennätyksellinen helleaalto alkoi. www.lapinkansa.fi/lapin-kesa-l...

The heatwave in Sodankylä has now lasted for 26 days. This is probably not only the longest heatwave in Lapland, but also the longest heatwave ever observed in Finland. Note that here a heatwave is defined with 3 consecutive days above 90th percentile, which is scientifically robust definition.

Inspired by @ketilisaksen.bsky.social post, I did the same analysis for Finland. In terms of 14-day average temperatures, the 2025 heatwave in Finland did not quite surpass the well-known 1972 and 2018 heatwaves. This is based on 10 km gridded observations.

The record-long streak of 30 °C in Finland finally ended yesterday. The outcome was an impressive 22 consecutive 30-degree days between 12 July and 2 August. Who would have believed in June? Not me at least.