Weather News

Named by the Spanish Met Service (AEMET), Claudia developed from a depression that emerged near Newfoundland on 9 November, before being absorbed into a broader cyclone west of the UK and becoming the dominant centre of a large low that impacted many parts of western Europe. On 13/14 November, warm air drawn north into the southern UK collided with colder air streaming south – the first, relatively weak attempt at the Arctic northerly that set in several days later. This clash led to marked frontogenesis over Wales and central England. Heavy rain, enhanced by orography and convective elements, resulted in widespread totals of 50–75mm, while Tafalog in the Vale of Ewyas, next to the River Honddu, recorded 119.6mm in the 33h between 2100 utc on 13 November and 0600 utc on 15 November. A major flooding incident was declared in Monmouth, with more than 50 properties affected. Meanwhile, across the continent, Portugal was severely impacted. Torrential rain, landslides and flooding triggered over 3400 emergency calls nationwide, with the worst damage reported from the Setúbal Peninsula (Lisbon) to the Algarve. A tornado with wind gusts up to 120kn struck Albufeira, destroying a campsite and hitting a nearby hotel, killing an 85-year-old British woman and injuring 28 others. In the Lisbon suburb of Fernão Ferro, a couple drowned after floodwaters surged through their home overnight. Along the Atlantic coast, Claudia also generated a powerful long-period swell, producing towering walls of water at the big-wave surf spot Nazaré, where surfers rode some of the largest waves of the season – in excess of 40 ft. As the storm approached Spain, AEMET issued a rare red alert for storms, strong winds and intense rainfall across central regions including Cáceres and Ávila, warning that up to 120mm of rain could fall within 12h. The deluge soon took its toll: widespread flooding engulfed Huelva, while parts of Galicia in the northwest saw as much as 150mm of rain in 24h. Rivers were overwhelmed, and a major route between Huelva and Seville collapsed as saturated ground gave way. Claudia struck during what became an exceptionally wet month for northwestern Spain. Several sites reported extremely high monthly rainfall totals, including Cee in Galicia, which recorded 415mm – almost double the region’s typical November rainfall of around 200–250mm. (Sources: Olive Press, IPMA, AEMET, Nazare Waves.) As daylight continued its inexorable reduction towards the northern hemisphere Winter Solstice, and thoughts for some turned to cold and snow, stratosphere watchers noticed hints of something brewing in the models regarding a slowing of the seasonal polar vortex. Having formed on cue in late August, its winds were generally below average strength until early November, when it strengthened to near normal for the time of year. Around this time, however, models began to hint at the possibility of a significant November warming event, possibly even a Sudden Stratospheric Warming (SSW). As tends to be the case nowadays, this was quickly latched onto in both social and mainstream media, snowballing into a narrative akin to ‘odds on for the coldest winter since 1963’ via numerous links to the 2018 ‘Beast from the East’. Speculation was further fuelled by a coincident spell of northerly winds in mid-November, which brought frequent snow showers and put many people into a frosty frame of mind. Over 25cm of snow was reported across parts of northern and eastern Scotland, eastern England, and even Pembrokeshire courtesy of the eponymous ‘Pembrokeshire Dangler’. In the event, the polar vortex, as measured by the mean zonal wind component at 10hPa and 60° N, reached its minimum strength on 28 November and was so close to zero (Figure 1) that whether the SSW qualified as ‘major’ (daily-mean zonal wind below zero, i.e. easterly) is within the range of uncertainty in the analysis. At least in ERA5 reanalysis, it is the joint earliest on record, tied with 28 November 1968. It also emerged the event was a ‘reflective’ type, where energy deposited in the stratosphere from tropospheric waves, responsible for slowing the polar vortex, was quickly either reflected or absorbed and retransmitted back down into the troposphere. This canonically leads to a strengthening of the North Atlantic jet rather than a weakening, favouring milder westerly regimes for Western Europe, which indeed were dominant during the first two-thirds of December. While things can change, often at short notice (!), the chances of dramatic cold during the rest of December, at the time of writing, look fairly remote. (Sources: ECMWF, X, The Mirror, The Liverpool Echo, Yahoo News, NOAA Ozone Watch, Met Office, Kodera et al. (2016) https://doi.org/10.1002/2015JD023359.) The 30th meeting of the UN Framework Convention on Climate Change (UNFCCC), commonly known as COP, took place from 10 to 21 November 2025 in Belém, Brazil, bringing together almost 60 000 delegates from across the globe. Framed by the Brazilian presidency as the ‘COP of implementation’, the summit aimed to shift global climate efforts from pledges to concrete actions, with an emphasis on adaptation, nature and climate justice. Delegates agreed on a streamlined set of global indicators to measure progress on adaptation and committed to tripling adaptation finance by 2035, a key step for climate-vulnerable nations. COP30 also advanced a just transition mechanism to support countries and communities moving to low-carbon economies. Progress was made on nature and forests through the launch of the Tropical Forests Forever Facility, designed to provide long-term finance to protect tropical forests. Inclusive participation was a notable feature of COP30, with the adoption of a gender-climate action plan and record engagement from Indigenous Peoples, whose contributions shaped discussions on land rights, biodiversity and resilience. However, major gaps remained. Efforts to secure a commitment to phase out fossil fuels failed after opposition from several oil-producing states. Although the presidency pledged to develop non-binding roadmaps on fossil fuels and forests, these sit outside the formal COP text. Climate finance commitments also faced criticism for long timelines and reliance on voluntary follow-through, with UN Secretary-General António Guterres warning that ‘the gap between where we are and what science demands remains dangerously wide’. The official host nation for the next summit has been announced as Turkey, who will host the conference in Antalya. An agreement was made between Turkey and Australia, who also bid for COP31, that while Turkey will be the host nation, the Australian minister will play a leading role in chairing negotiations. (Sources: COP30, WMO, United Nations, UNFCCC, Climate Action.) The ‘official’ Australian tropical cyclone season (defined by the Bureau of Meteorology, BOM, as 1 November to 30 April) got off to a quick start with Tropical Storm Fina forming on 18 November over the Timor Sea, just north of the Tiwi Islands. Over the following days, Fina meandered east before making a sharp turn south and southwest, making its first landfall on the Coburg Peninsula of Northern Territory on 21 November as a Category 2 (Aus. scale) cyclone. This was the first November cyclone to make landfall in Australia since Alessia in 2013, and the joint earliest-in-season landfall with Ines in 1973. Fina went on to become a Category 4 Severe Tropical Cyclone, brushing past Darwin along the way, causing widespread damage and disruption, including loss of power to almost 20 000 homes. Its final landfall was at the Berkeley River mouth on the Kimberley coastline, where a luxury wilderness resort, only accessible by plane or boat, took a direct hit. Fortunately, the site was unoccupied except for two caretakers due to it being outside the tourist season, as 3 of the 18 villas were reported destroyed, with total loss of water and power across the site. The Australian monsoon, however, appears behind schedule, with an update from BOM in early December stating wind patterns in the tropics were more akin to October or November than early December. Forecasts currently suggest an onset date of early 2026, against the average onset date at Darwin of 28 December. Looking across the tropics to the Central Pacific, BOM also declared in late November that the negative SST anomalies present for some time have finally become coupled to the atmosphere, indicating a La Niña episode is underway. The ‘Bureau’ also made headlines at the end of November, as it was revealed that its much-maligned website refresh at the end of October cost not A$4.1 million as previously stated, but a staggering A$96.5 million – almost 24 times as much. According to news reports, BOM was ‘flooded with a deluge of complaints’ within hours of the site going live, and a week later the acting head of the agency was forced to apologise. Appearing before a senate hearing in the Australian Parliament in early December, Dr Stuart Minchin admitted the refresh was not ‘right for some sectors of the community’, and in the highly politically charged meeting the whole affair was labelled a ‘nightmare case study in contract failure’. This comes as the Met Office prepares to launch its refreshed website design and smartphone app, promising to be ‘simpler, more accessible and inspired by your feedback’. (Sources: NOAA Historical Hurricane Tracks, BOM, ABC News, news.com.au, BBC News, Met Office.) Research published in 2024 revealed that the Hektoria Glacier, on the eastern Antarctic Peninsula in the British Antarctic Territory, underwent one of the fastest observed glacier retreats on record. Between January 2022 and March 2023, it retreated by a dramatic 25km, with 8km lost in just two months. New research released in November 2025 reveals this retreat was driven primarily by rapid ice-plain calving (a destabilisation and collapse triggered by the glacier’s underlying bed shape), rather than atmospheric or oceanic conditions, as previously thought. Hektoria sits on an ice plain, a flat stretch of bedrock below sea level. Once destabilisation began, huge slabs of grounded ice lost support, floated away and calved rapidly into the Southern Ocean. Seismic tremors recorded during the collapse confirm the glacier had been grounded, meaning this was real land-ice loss, not merely floating ice disintegration. The meltwater has since poured into the Southern Ocean. Freshwater influx here could disrupt local salinity and mixing, potentially allowing relatively warm deep water to reach remaining ice and accelerate further melt. Though small by Antarctic standards (just 115 square miles), Hektoria shares its vulnerable ice-plain geometry with much larger glaciers. Future collapses of this type could have enormous implications for sea-level rise, ocean currents, and global climate feedbacks. (Sources: Ochwat et al. (2025) https://doi.org/10.1038/s41561-025-01802-4, Swansea University, Science Daily, Fluegel and Walker (2024) https://doi.org/10.1029/2024GL110592.) In last month’s news, we reported on the latest upgrade to ECMWF’s Integrated Forecasting System, provisionally pencilled in for the first quarter of 2026. The latest (at time of writing) is that due to additional work required, this has now been pushed back to early in the second quarter. (Source: ECMWF.)