High temperatures over the Antarctic Peninsula in June 2026 strengthened by human-driven climate change 

Contact Authors

• Neven S. Fučkar (Environmental Change Institute, University of Oxford, UK) - neven.fuckar@ouce.ox.ac.uk EN/HR

• Davide Faranda (IPSL-CNRS, Paris, France) - davide.faranda@lsce.ipsl.fr  - EN/FR/IT

• Ryan S. Williams (British Antarctic Survey, Cambridge, UK) - rywill@bas.ac.uk  - EN

• Thomas J. Bracegirdle (British Antarctic Survey, Cambridge, UK) - tjbra@bas.ac.uk  - EN

• Steve Colwell (British Antarctic Survey, Cambridge, UK) - src@bas.ac.uk  - EN

• Yuiko Ichikawa (Environmental Change Institute, University of Oxford, UK) - yuiko.ichikawa@ouce.ox.ac.uk EN/JP

Citation

• Fučkar, N. S., Faranda, D., Williams, R., Bracegirdle, T., Colwell, S., & Ichikawa, Y. (2026). High temperatures over the Antarctic Peninsula in June 2026 strengthened by human-driven climate change. ClimaMeter, Institut Pierre Simon Laplace, CNRS. https://doi.org/10.5281/zenodo.20809265

Press Summary

• Meteorological conditions like those leading to the Antarctic Peninsula heatwave in early June 2026 are up to 3 °C warmer than they were in the past at locations of research stations and potentially substantially higher (up to 7 °C) at other Peninsula locations according to ERA5 .

• This extreme event is associated with rare meteorological conditions.

• Temperatures above 0°C in June in the Antarctic highlights the need to consider potential impacts of rain and melt on glaciers and ice shelves in all seasons including southern hemisphere winter.

• We conclude that the anomalous high temperatures during the June 2026 Antarctic Peninsula heatwave were significantly strengthened by human-driven climate change, while natural climate variability likely played a secondary role.

Event Description

Antarctica, the southernmost continent on Earth, is characterized by persistently below-freezing surface conditions across most of its regions. While the Antarctic Peninsula has the mildest climate on the continent, profoundly influenced by the atmospheric dynamics and surface conditions over the Southern Ocean, daily mean near-surface air temperatures in June are generally between -10°C and -5°C.  

The beginning of meteorological austral winter (June-August) this year was exceptionally warm culminating on the 5th and 6th of June with some stations across the Antarctic Peninsula observing provisionally their highest recorded temperatures.  The most unprecedented observations were taken at the Esperanza base (Argentina) on the Trinity Peninsula or Graham Land – the northernmost part of the Antarctic Peninsula – where temperature reached maximum of 15.4°C on 6 June 2026, surpassing the previous local June record of 13.3°C set in 1998. This condition was about 20°C above the long-term June average of -6.2°C and close to the daily maximum temperature in Edinburgh, UK, on the same day. The extreme temperature event was not confined to a single station. Marambio base (Argentina) reached 11.8°C, exceeding its previous June record of 9.2°C, while San Martín base (Argentina) recorded 9.4°C, surpassing its previous record of 7.8°C.

An analysis encompassing few more locations further south along the Antarctic Peninsula, including Faraday/Vernadsky (UK/Ukraine) and Rothera (UK) research stations, also shows that such high temperatures with daily mean values above freezing affected a large portion of the Peninsula rather than being a localised anomaly. The Figure below show that daily mean temperatures on the 5th and 6th of June 2026 (red dots) were mostly above the 99th (or at least above the 95th) percentile for this time of the year at the Esperanza, Marambio, Faraday/Vernadsky and Rothera stations. Using these point observations from 1980 to present, the mean climatology (black dashed line) is calculated by applying a harmonic filter (cutoff = 3) to the arithmetic daily mean climatology, with the percentile estimates derived with respect to this baseline and taking into account a 31-day rolling window for a more robust estimation.   

The first ClimaMeter figure shows that this event was associated with unusually strong northerly airflows that transported warm maritime air over the Antarctic Peninsula. More specifically, the surface pressure anomalies reveal an anticyclonic flow (more than +20 hPa compared to the 1950–present climatology) centred over the Southern Ocean between the Falkland Islands and the Trinity Peninsula associated with high temperatures across the Antarctic Peninsula and western Weddell Sea (more than +20°C compared to the 1950–present climatology). High anomalous temperatures over the eastern Antarctic Peninsula and western Weddell Sea were associated with anomalous sensible heat transport from the north and the foehn warming effect. Foehn winds are warm, dry winds that typically descend the eastern slopes of the Antarctic Peninsula as localized foehn wind jets, often driving significant surface melt and rapid temperature increases (Clem et al., 2026). 

The ERA5 reanalysis captured the foehn warming associated with cross-peninsula flow, with latent heat release from upstream precipitation and cloud formation. Station observations at Esperanza support the importance of the foehn effect, with a strong west-southwesterly wind recorded on 6 June. The strong northerly inflow west of the Antarctic Peninsula and the cross-peninsula winds both persisted more than a day, preconditioning the warming event to peak on 6 June. Cloud formation may also have reduced radiative cooling under dark winter skies, further enhancing the warming during the subsequent days. 

In addition, there is a potential role of exceptionally low sea-ice cover in the Bellingshausen Sea west of the Antarctic Peninsula. Satellite observations showed that the region was missing roughly 650,000 km² of winter sea ice, an area comparable to the size of France. The reduction of sea ice there can reduce the cooling of incoming air from west and north, allowing warmer conditions to penetrate farther east and south, and intensify the heatwave over glaciers and ice shelves. 

This extreme temperature event over the Antarctic Peninsula illustrates that understanding the potential impacts of melt conditions requires a full perspective across all seasons. Surface mass balance, ice shelf stability and ecosystems are all key considerations in the face of intensification of extreme winter warm spells in one of the most rapidly warming regions on Earth.

Climate and Data Background for the Analysis

As human-induced greenhouse gas and aerosol emissions, and land-use change continue to alter the Earth's climate system, various types of extreme weather and climate events are becoming more intense and/or more frequent across many parts of the world (IPCC AR6 WGI Chapter 11). Although the Antarctic Peninsula is among the fastest-warming regions on Earth, with warming rates reaching up to twice the global average, research on the attribution of extreme events and their impacts in Antarctica remains an emerging area that warrants greater scientific attention.

In addition to the challenge of disentangling long-term anthropogenically forced climate trends from pronounced internal climate variability, Antarctica faces potential risk of significant loss of sea ice, ice shelf collapse and glacier recession. Hence, this study should motivate also further research on attribution of the impacts of extreme events to better understand the dynamic of extreme events now and into the future and their roles in affecting  global climate, ocean circulation, sea level, ecosystems and ultimately society.       

The approach applied here uses observationally-constrained historical data - ERA5 reanalysis, complemented with GFS forecasts for up-to-date coverage - and does not rely on un-constrained numerical model simulations. This framework compares how the selected meteorological conditions captured by surface pressure over the relevant spatial domain have changed between the first half of the historical period (1950-1987) as "past" and the second part (1988-2024) as "present", and whether such changes are likely due to natural climate variability or human-induced climate change.

ClimaMeter Analysis 

For our study of the 5-6 June 2026 high-temperature event (2-day mean values) over the Antarctic Peninsula we focus on a wider region encompassing large-scale atmospheric circulation patterns crucial for understanding weather influencing the Peninsula’s surface conditions. The selected region for our analysis of surface pressure and related variables is [80°W–40°W, 75°S–50°s].     

Surface pressure changes between two periods show only relevant decrease (down to -5 hPa) over eastern Antarctic Peninsula and the Weddell Sea. The associated temperature changes reveal a substantial warming across the Peninsula and western Weddell Sea up to +7°C higher in the “present” than their “past” counterpart, with the most pronounced increases over numerous glaciers and ice shelves. These results are consistent with long-term warming trend in reanalysis products observed in the region. Wind speed changes show a modest increase (up to +3 km/h) in the region of elevated near-surface air temperature. While the precipitation changes between two periods show drier conditions over northern Peninsula and wetter conditions over southern Peninsula potentially indicating southern shift of westerly winds over the region with relevant changes in surface pressure.    

Similar past events indicate a seasonal shift from the “past” to the “present” conditions, with a higher fraction of cases now occurring before the southern hemisphere winter (higher in May, while lower in June and July). This can be interpretation that such extreme heat events are occurring earlier in the southern hemisphere autumn under present-day conditions. Changes at the selected research stations show that they experienced significantly warmer conditions (up to +3 °C) during this 2-day event compared to similar “past” events, while precipitation changes are highly heterogenous (from -3.5 mm/day to +1.5 mm/day). The associated wind speed changes were mostly positive (up to +3 km/h).

Overall, our results suggest that meteorological conditions like those of the 5-6 June 2026 heatwave over the Antarctic Peninsula are now associated with significantly warmer surface conditions than in the “past”, consistent with the critical influence of human-induced climate change. The large-scale atmospheric pattern mostly resembles previous events but in the present conditions have depressed values of surface pressure over eastern Antarctic Peninsula and the Weddell Sea by background climate change. Natural variability represented by El Niño-Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), and the Pacific Decadal Oscillation (PDO) appears to have played only a minor role in shaping the event.

Conclusion

Based on the above analysis, we conclude that the large-scale atmospheric patterns associated with the 5–6 June 2026 Antarctic Peninsula heatwave are up to +3 °C warmer than they than they would have been under comparable conditions in the past at research station locations and potentially substantially higher (up to +7 °C) at other Peninsula locations according to ERA5. This 2-day event is also characterized by surface pressure negative anomalies of down to -5 hPa and exhibit a seasonal shift toward earlier occurrences in the austral autumn compared with analogous historical events. We therefore interpret this exceptional heatwave as the result of a rare meteorological configuration whose intensity has been amplified by human-induced climate change.

Additional References

Clem, K.R., et al., 2025, Chapter 7. Meteorology and Climate of Antarctica, in Taschetto, A.S., et al., (eds), Meteorology and Climate of the Southern Hemisphere, Cambridge University Press, pp 549, https://doi.org/10.1017/9781009352680