A Met Office Yellow Weather Warning for heavy rain has been activated across wide swaths of England and Wales, starting Friday night, November 28, 2025, and continuing through Saturday, November 29. The warning, issued at 10:43 UTC on Friday, signals a significant burst of rainfall that could bring up to 50 millimeters in many areas — and potentially 60 to 80 millimeters over high ground — raising fears of localized flooding and travel chaos. What makes this event even more unusual is the backdrop: meteorologists are watching for a rare, early-season sudden stratospheric warming event, forecasted to unfold in the final days of November. Aidan McGivern, a senior Met Office meteorologist and weather presenter, flagged the phenomenon in a forecast video published November 21, noting, "We don't often see it happening at the end of November, start of December."
What’s Happening on the Ground?
The rain is expected to begin in southwest England — areas like Devon, Cornwall, and Somerset — late Friday night, then sweep northeastward across the country on Saturday. By Saturday night, it will clear into the North Sea. The heaviest downpours aren’t evenly distributed; while 20–30 mm is likely across most of the warned zone, pockets in the Pennines, Welsh uplands, and the Cotswolds could see far more. The Met Office warns that strong winds, especially across eastern England, may accompany the rain, turning slippery roads into hazardous corridors.
The affected regions are extensive: from the East Midlands (Derbyshire, Nottinghamshire, Lincolnshire) to East Anglia (Norfolk, Suffolk), across London and the South East (Buckinghamshire, Surrey, Kent), and deep into the South West (Bristol, Dorset, Wiltshire). Even the Isle of Wight and Medway aren’t spared. Local authorities in places like Bath and North East Somerset and Plymouth have begun pre-positioning sandbags and flood response teams. Schools in rural areas near rivers are preparing contingency plans.
The Stratospheric Wildcard
While the rain dominates headlines, the real scientific intrigue lies above the clouds — in the stratosphere, 10 to 50 kilometers above Earth’s surface. A sudden stratospheric warming (SSW) event occurs when polar vortex winds weaken or reverse, causing temperatures to spike by as much as 50°C in just days. These events, while not uncommon in winter, are highly unusual this early. According to McGivern’s analysis, stratospheric temperatures had been near average until mid-November, then began climbing sharply.
"There’s a lot of uncertainty," he admitted. "The lag effect between the stratospheric shift and surface weather can be two to four weeks. So if this happens late this month, we could be looking at a colder December — or we could not." The current forecast doesn’t show immediate cold: temperatures remain above seasonal norms through Saturday. But the SSW could be a silent trigger for a later cold snap, possibly in the second half of December. That’s why climatologists are watching closely. The last major SSW in the UK was in January 2021, which preceded a prolonged freeze.
Why This Matters Beyond the Rain
It’s easy to treat this as just another wet weekend. But the combination of immediate flooding risk and potential long-term climate disruption makes this more than routine. The Met Office has noted that climate change is increasing the frequency of extreme rainfall events. In the past decade, the UK has seen a 15% rise in heavy precipitation days. This week’s deluge fits that pattern.
Equally concerning is the timing of the SSW. Historically, these events have been linked to more persistent cold spells — think 2010’s "Big Freeze" or 2018’s "Beast from the East." But recent studies suggest climate change may be altering how SSWs translate to surface weather. Some models now show they’re more likely to cause wet, windy winters than deep freezes. The UK could be witnessing that shift in real time.
What’s Next?
By Sunday, the rain will be gone. But the real story is just beginning. The Met Office will release its December outlook on December 3. If the stratospheric warming strengthens, expect more updates — possibly even a cold weather warning by mid-December. In the meantime, residents in the warned areas are urged to check local flood alerts, avoid unnecessary travel on Saturday, and secure outdoor items that could become projectiles in strong winds.
"We’re not saying it’s going to be a snowy Christmas," McGivern added. "But we’re saying: don’t ignore the signals. The atmosphere is sending mixed messages — and that’s what makes this so interesting."
What’s Been Seen Before?
Similar SSW events occurred in 2010, 2018, and 2021 — each followed by weeks of below-average temperatures and snow. But 2023’s minor SSW, which also occurred in late November, led to a wet, mild December instead. That’s the uncertainty meteorologists are grappling with now. Climate models are split: half suggest a colder December; half say the Atlantic will keep warmth flowing in. The only way to know for sure is to wait — and watch the stratosphere.
Frequently Asked Questions
How much rain is expected, and where is flooding most likely?
Up to 50 mm of rain is expected across most of the warned areas, with 60–80 mm possible over high ground like the Pennines, Brecon Beacons, and Dartmoor. Flooding is most likely near rivers in Derbyshire, Somerset, and East Sussex, where ground is already saturated from recent rainfall. Emergency services have pre-deployed pumps in 12 high-risk towns.
Why is a sudden stratospheric warming event unusual in late November?
SSWs typically occur between December and February, when the polar vortex is strongest. A minor event this early is rare — only three have been recorded in November since 1950. The current warming is driven by unusually strong planetary waves from the Pacific, which are being amplified by warmer-than-average sea surface temperatures — a pattern linked to climate change.
Will this lead to a cold December like the "Beast from the East"?
Not necessarily. While SSWs can trigger cold spells, recent patterns show they’re more likely to cause wet, stormy weather. The UK’s jet stream may weaken and meander, bringing alternating bands of rain and milder air. The Met Office’s December outlook, due December 3, will clarify whether a prolonged cold spell is likely.
What should people do right now?
Avoid unnecessary travel on Saturday, especially through low-lying or hilly areas. Check your local council’s flood alert page. Secure loose garden items, and ensure drains are clear. If you live near a river, have an emergency kit ready. The Met Office advises against walking or driving through floodwater — just 30 cm can sweep away a car.
Is this linked to climate change?
Yes, in two ways. Warmer oceans are fueling stronger atmospheric waves that trigger SSWs earlier in the season. At the same time, a warmer atmosphere holds more moisture — increasing the intensity of rainfall. The UK has seen a 15% rise in extreme rainfall events since 2000, and this event fits that trend.
When will we know if the stratospheric warming will impact December weather?
The lag effect means impacts may not appear until mid-December. The Met Office will issue its official December forecast on December 3, based on updated stratospheric data. If the warming persists, expect more frequent storm systems and possible cold outbreaks. If it fades, December could remain mild and wet — no snow expected.
