Although there’s still 8 days remaining, Here’s a scoring of my 2024-25 winter forecast.

Here’s what was said back on the 24th November 2024.

Global drivers/teleconnections in play as of late November.

What we know…

• Warm oceans overall

• NEUTRAL to Weak La Nina

• Cold PDO (Pacific Decadal Oscillation)

• Warm AMO (Atlantic Multidecadal Oscillation)

• Neutral IOD (Indian Ocean Dipole)

• West QBO (Quasi-biennial Oscillation)

• Solar Maximum (25)

THE 2024-25 WINTER VERDICT

I’m going with my gut and my gut is saying mild outdoes cold overall.

However, a mild December-February overall DOESN’T mean NO COLD. I suspect we could see a few wild swings between mild, perhaps very mild to cold.

The SST anomalies are one thing and stratosphere another. The uniform ‘warm Indian Ocean to Indonesia region’ suggests the MJO could get stuck in the stormier phases of 2 into 3 and mild 4-5 resulting in a predominantly +AO/NAO. MILD for NW Europe.

However, the recent weeks of westerly winds blowing over the west tropical Pacific could help move the MJO from Indian to Pacific and more importantly CENTRAL Pacific (phase 7-8-1) and therefore shifting the AO/NAO negative.

I believe we have some ‘decent periods of cold‘ as we should see periods with the MJO crossing the central Pacific (if waters DON’T cool much) but I think the winter default position will be 2-3 into 4-5 resulting in a lot of Atlantic dominance for NW Europe.

The polar vortex behavior is the elephant in the room for me. It’s expected strengthening into December aided by a lack of high latitude blocking (+AO/NAO) and MJO phase 2-3 into 4-5 isn’t a good indicator for anything other than mild, perhaps stormy at times through weeks 1-2, perhaps even 3 of December.

The graphic below shows the mean zonal winds at 10mb, strengthening through much of December, this supports the idea of low heights over the arctic (+AO) and less friction within the lower 50mb level of the stratosphere.

The MJO I think will head back towards 7-8 mid to late December which ‘may’ support a colder final 5 to 10 days of December.

One cannot rule out an SSW which would support a more prolonged and stronger period of cold weather.

There’s little evidence of any significant weakening of the polar vortex much before Christmas. The neutral ENSO-Solar Max-West QBO suggests a 50/50 chance for an SSW and without one, I believe MILD will be stronger and longer than any cold spells but the cold spells we do see, could be substantial with 2 or 3 amplified rotations through phases 7-8-1 like observed during the autumn just ending.

An active MJO over the Indian Ocean is likely to lead to some ‘minor displacement’ of the polar vortex and likely cross polar flow from Siberia to N America. Meaning arctic intrusions into Canada and US but this likely fires up the Atlantic jet which forces mild, unsettled weather into NW Europe.

Monthly Breakdown

DECEMBER 2024

Mild with opportunity for a few named storms into W/NW Europe, colder with heavy snowfall into the Balkans and east Europe.

As MJO is expected to return towards phase 6 we could see another period of stagnant high pressure dominance which may result in a dry but perhaps chilly spell with lingering fog etc mid month.

Late December offers an opportunity for something colder towards Christmas-New Year and a slightly higher chance for snow during the holidays!

SLIGHTLY MILDER THAN AVERAGE WESTERN EUROPE, COLDER EAST, SOUTHEAST EUROPE

JANUARY 2025

Depending on the behavior of the polar vortex and likely MJO return towards the Indian Ocean, I would say mild Atlantic conditions remain through the first 10-15 days of January with another opportunity for something colder through the final 10-15 days of the month.

AVERAGE, POSSIBLY SLIGHTLY BELOW AVERAGE OVERALL WITH SWINGS BETWEEN MILD AND COLD

FEBRUARY 2025

Again, a lot depends on the polar vortex but I think yet another month sees spells of both mild and cold perhaps stormy.

Potentially COLDER THAN AVERAGE

Milder than average winter overall

READ FULL FORECAST: Europe Winter Forecast 2024-25

What Happened…

The MJO and polar vortex have behaved largely as anticipated with rotations through the cold (7-8), stormy (2-3) and warm (4-5) phases with rise and fall of the Arctic Oscillation in response as well as strengthening and minor weakening (mostly stretching) of the polar vortex.

Back and fourths between mild and cold.

Here’s the actual UK/Ireland temperature anomaly month-by-month as per CDAS 0.5.

December ’24

January ’25

February ’25 (through 18th)

Past 90 days

As expected, we observed a milder than average December with combination of milder phases of the MJO and strong polar vortex. The AO was negative then positive with a negative end, this resulted in the ‘expected colder period’ between Christmas and New Year.

Though January saw a colder first half, less cold second (opposite what was said), the idea was good given that predicting exact timings of mild-cold spells is impossible so far in advance but it happened nevertheless.

Overall the cold early January was strongest since 2010 with coldest January max since 1982 and coldest January minimum since 2010. Overall it was colder than average as forecast.

February was believed to be colder than average and thus far, it is. Again, like January, I believed cold and mild spells with colder than average overall. The month will wind up average or slightly below average which is a decent call. I did believe it would be colder but if you look at it objectively, I think you’ll agree that the synoptics was there. Colder than normal occurred, just not as strong as thought initially.

Overall I believe the forecast was good given the ups and downs. I guess you could say it turned out slightly colder than thought given we’re likely to wind up around average for the Dec-Feb period while I said slightly milder than average.

Overall Score: 7.5 out of 10!