Niño–Vortex Watch

Readings as of 30 Oct 2026
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A very strong El Niño is still building in the tropical Pacific while the Arctic stratospheric vortex is forecast to break down weeks earlier than ever recorded. This board tracks both: the numbers, where they are, what to watch next, and the latest reporting.

El Niño Advisory · very strong, still strengthening Polar vortex · major warming forecast 4–6 Nov UK · settled & foggy to ~12 Nov, then unsettled

Tropical Pacific · sea surface

El Niño

+3.3°CNiño 3.4 weekly anomaly, week centred 14 Oct (IRI)

−16.6SOI, 30 days to 25 Oct (El Niño below −7)

+0.69°CIndian Ocean Dipole, positive 7 weeks

83%Chance Oct–Dec beats every event since 1950 (CPC)

Relative indices subtract the warming of the whole tropics, so they read lower than the traditional index for the same ocean. All 27 models in the IRI plume keep the event "very strong" through Dec–Feb, and NOAA expects El Niño to last into Mar–May 2027.

Arctic stratosphere · 10 hPa, 60°N

Polar vortex

—until the forecast wind reversal (centre of the 4–6 Nov window)

A major sudden stratospheric warming is called when the west-to-east winds at 60°N and 10 hPa turn around. The likeliest outcome is a brief split that re-merges as a displaced vortex. Any surface cold usually follows one to four weeks later, and not every event reaches the ground.

United Kingdom · what it could mean here

The UK picture

The two drivers pull the UK in opposite directions. El Niño tilts late autumn and early winter towards wet, stormy and mild. A collapsed polar vortex tilts the following weeks towards blocking and cold. Right now the Met Office outlook shows neither extreme: a quiet, foggy spell, then the Atlantic returning.

Met Office long-range vs the stratosphere

Next five weeks

Met Office outlook (late October): high pressure brings mostly dry weather from 3 to 12 November, with fog that may linger all day and overnight frost. From 13 to 27 November rain and strong winds become more likely, wettest in the north and west, with temperatures near or slightly above normal. Neither outlook mentions the polar vortex yet.

Status as of 30 Oct

Signals to watch

Pending
Winds reverse at 60°N, 10 hPaForecast 4–6 Nov; 61% blended chance. This is the official start of a major warming.
Watch
Warming works its way downCan take days to weeks to reach UK weather. Watch mid-November to early December.
Active
Blocking high over the UKHigh pressure dominates into the first part of November: fog, frost, little rain.
Not yet
Easterly or northerly windsThe usual route for severe cold. Not in any current outlook; Atlantic westerlies are expected back mid-month.
Not yet
Met Office flags colder riskThe 28 Oct outlook makes no mention of the vortex. A change here would be the clearest UK signal.

El Niño tends to bring

Wetter, stormier, milder weather made more likely in late autumn and early winter. The Met Office gave a warm, wet autumn 1.5 to 2 times the usual odds.
A weaker polar vortex later in winter, after El Niño peaks, raising the chance of cold spells from late winter.
Then the opposite the following winter: Met Office research finds El Niño is often followed by a positive North Atlantic Oscillation a year on, which means milder, wetter winters.

A vortex collapse tends to bring

A cold spell more often than not, though not every time. The Met Office describes a major warming as greatly raising the risk of wintry weather.
Blocking high pressure to the north, with easterly winds that carry snow showers into eastern Britain.
Muted effects this early: in November there is less deep cold air in the Arctic to draw south than in mid-winter.

Past winters to compare

Winter	Set-up	What the UK got
1997/98	Very strong El Niño	A mild winter with no lasting cold.
2009/10	Moderate El Niño, strongly negative NAO	The coldest UK winter since 1978/79, with repeated heavy snow.
2015/16	Very strong El Niño	Very mild; December 2015 was the UK's warmest and wettest December on record, with severe flooding in northern England and Scotland.
Feb–Mar 2018	Major stratospheric warming on 12 Feb	The "Beast from the East" about two weeks later: bitter easterly winds and heavy snow.

A handful of past winters, not a forecast. The two strongest El Niños both gave mild UK winters, but neither had a November vortex collapse alongside.