January 2025 has been a mixed month but largely dominated by a -AO/NAO hemispheric setup with likely coldest opening 10 days since 2010 for both UK and Ireland.

The cold first half broke around the 12th as northerlies were abruptly replaced by southerlies causing the temperature to lift by some 25-32C within a mere 72 hours in W/N UK, less so over S/SE UK were low level cold became trapped beneath high pressure. The cold first 10/12 days was followed by a less cold but not entirely mild following 20 days.

Note the textbook Greenland positive/N Europe negative through the first 10 days at 500mb below.

Here’s that same opening 10 day 2m temperature anomaly!

Europe view

The contrast between Iceland, UK/Ireland and Scandinavia compared to much of the rest of Europe is notable.

The back and forth temperature swings we’ve become accustomed to in recent months persisted through January along with swings between high and low pressure, wet spells and dry spells.

For Europe, January will go down as one of the mildest while for UK, Ireland and Iceland, colder than average.

This slightly colder than average January follows a mild December.

When combining Dec-Jan this is the temp anomaly as per CDAS.

With the less cold 2nd half to the month came a more changeable one. As the MJO drifted out of phases 7-8 and amplified into phases 1-2-3 so Siberian air began to flow up and over the pole and down into North America. By doing so the Atlantic jet stream strengthened and flattened but this coincided with a strengthening of high pressure over Europe.

The tightening up of the Atlantic thermal gradient gave birth to deep winter cyclones and we here in NW Europe bore the full force of a renewed stormy spell between the 18th and 25th. In came Storm Eowyn, the deepest low in decades to affect Ireland while it was the UK’s deepest since 2013. This system affected Ireland, Northern Ireland, Scotland and northern England.

A further two more named systems followed Eowyn but taking a more southerly path, Storm Herminia and Ivor affected more southern England, France, northern Spain and Portugal.

While we observed a pattern change to less cold around 12th January, what stopped the ‘wipe out’ of the cold anomaly (UK/Ire) thereafter was low level cold trapped beneath a stagnant high which parked over the near continent for a week to 10 days after (12-22nd), it’s the same high which originated near Iceland and drifted south bringing the cold initially but lost it’s cold air with time at a more southerly latitude and surrounded by milder air, an inversion developed and despite 850s of +5 to +8C, surface temps across S/E England were lower while southerlies around it’s periphery warmed Ireland, NI and Scotland.

A temp flip occurred with the arrival of the stormier 24th through 28th, enough ocean modified cold air allowed temps to remain nearer average to slightly below across Ireland, NI and Scotland but milder for Eng and Wales.

MET OFFICE: Sunny and cool January kicks off the new year

Colder than average January in the sunshine

Thanks largely to an early month cold period, the UK’s January average mean temperature was 3°C, which is 0.9°C lower than the current long-term average.

The map below shows UK daily temperatures in the month compared to the long term average. 

It was a sunny month!

Relatively wet south, dry north.

January 2025 Monthly Weather Report

Highest Maximum 15.7°C on 14th at Cassley (Sutherland, 99mAMSL)
also on 15th at Aboyne No 2 (Aberdeenshire, 140mAMSL)
Lowest Maximum -10.8°C on 10th at Altnaharra No 2 (Sutherland, 81mAMSL)
Highest Minimum 11.1°C on 6th at Frittenden (Kent, 38mAMSL)
Lowest Minimum -18.9°C on 11th at Altnaharra No 2 (Sutherland, 81mAMSL)
Lowest Grass
Minimum -15.0°C on 11th at Oyne No 2 (Aberdeenshire, 116mAMSL)
Most Rainfall 94.0mm on 13th at Seathwaite (Cumbria, 129mAMSL)
Most Sunshine 8.0hr on 15th at Liscombe (Somerset, 348mAMSL)
Highest Gust 87Kt 100mph on 24th at Drumalbin (Lanarkshire, 245mAMSL)
Highest Gust
(mountain*) 117Kt 135mph on 24th at Cairnwell (Aberdeenshire, 928mAMSL)
Greatest Snow
Depth at 0900
UTC
26cm on 9th at Loch Glascarnoch (Ross & Cromarty, 269mAMSL)

My January Stats

My January Highlights

Record coldest day & night…

Two ‘Ice days’ with both max’s at or below -2°C!

First ‘double digits’ below 0°C

Colder than last January & significantly drier than previous month!

23 nights below 0°C!

Record low pressure!

UK, Ireland & Europe (some Global) Highlights

3rd Jan: Via Thierry Goose: Sukayu reached a #snow depth of 413 cm, exceeding 400 cm on Jan. 2, breaking the Japanese record for the earliest station [JMA stations] to exceed 400 cm since records began! The previous record was on Jan. 18, so Sukayu broke its own Japanese record by more than 2 weeks!

4th Jan: Frigid temperatures at mid-altitude sites and sinkholes in France & Switzerland! -37.8°C Sägistalsee -33.2°C Amburnex-Combe & Hintergräppelen -33.1°C Brizon-Doline de Solaison -31.1°C La Brévine -29.9°C La Chaux-d’Abel -28.6°C Glattalp -28.1°C Reculfoz-Combe

4th Jan: Coldest of winter so far in Canada with -49.1C at Mayo and Pelly Ranch, Yukon.

6th Jan: Big north-south temperature contrast for UK to begin 6th Jan.

8th Jan: -38.9C in Savukoski-Tulppio is Finland’s coldest night of winter so far.

10th Jan: Low of -14.5C early on the 10th Jan is the UK’s coldest night of winter so far.

10th Jan: High of -10.8C at Altnaharra, Surtherland is the UK’s coldest for January since 1982.

11th Jan: -18.9C recorded at Altnaharra, Sutherland is the UK’s coldest January night since 2010.

Some other cold lows.

The Highland Weather network recorded -20C in the central Highlands just east of Carrbridge.

12th Jan: Low of 3.6C at Abu Samra, Qatar set’s a new national record low for January surpassing previous record of 3.8C in 1964.

14th Jan: Coldest night in France (nationwide) since late February 2018.

14th Jan: INCREDIBLE (RECORD) WARM-UP IN HIGHLAND SCOTLAND… After highs of -9 and -10C on the Fri/Sat (10th/11th) and lows near -19C at Altnaharra, highs jumped to 9.7C Sunday, 11.5C Monday and 14.3C Tuesday 14th).

It reached 15.7C in Cassely, Surtherland and Aboyne, Aberdeen on 14th/15th respectively.

18th Jan: -61C recorded at Summit Camp, coldest for NH this winter and first -60C for 2 years in Greenland.

20th/21st Jan: Geraldton, South Australia recorded a high of 49.3C which ties their all-time record. 8th highest for S Aus and 1.4C off the all-time national record. -59C wind chill reported in Baker Lake, Nunavut, -41.1C/-42F air temp recorded in Minnesota on Inauguration Day.

24th Jan: STORM EOWYN

An official wind gust of 114 mph was recorded at Mace Head, Co Galway which is a new all-time wind record for Ireland replacing the previous record of 113 mph in 1945.

Magilligan, Co Londonderry reported a mean sea level pressure of 948.1mb as the centre of Storm Eowyn made it’s closest approach to Northern Ireland. This is a new January record low pressure for Northern Ireland and lowest since 1900.

The ‘Weather & Radar UK’ team recorded a wind gust of 118 mph on the the coast of Co Clare, Ireland as seen below.

Unofficial wind gusts of up to 206 kph or 128 mph was recorded on on Aran Islands in Galway Bay, Ireland.

25th Jan: Exceptionally high temperatures in Europe with up to 21.8°C in #France, 18.8°C in #Austria, 18.7°C in #Germany, 18.3°C in Liechtenstein & 18.1°C in #Switzerland. Dozens of monthly records have been broken, like Strasbourg, Grenoble, Chambéry, Annecy, Geneva, Bregenz, Nyon, etc.

According to Rutgers snow lab, January 2025 was above normal for the UK and Ireland and unsurprisingly below normal across much of Europe.

TO BE COMPLETED…

January Ends & February Begins With the MJO Phases 4-5 & +AO/NAO

What’s notable is that despite the cold January for North America, coolish January for UK/Ireland but warm Europe is the polar vortex has been strong with both core temp and mean zonal wind at 10 and 30mb as seen below.

SO FAR

Current anomaly at 10mb.

Current & projected mean zonal wind.

We’ve observed a strong yet stretched PV structure within both stratosphere and troposphere favoring a cold North America but mild Europe.

We have an interesting ‘final test’ of this winter coming up.

With +AO/NAO and deep Atlantic trough and Europe ridge, we’re seeing a pretty pronounced northward ‘heat transfer’ from subtropics into high latitudes which is set to pump heights. This forces a bulging of the tropospheric layer and in turn creates a frictional drag up into the stratosphere.

Note the double peaks in the 500mb height field below, TWO distinct ‘positive anomalies’.

When looking at the 10mb level and anomaly, you can see the influence these two ‘atmospheric mountains’ have on the polar vortex by squeezing from both Alaska and Eurasia side attempting to split the vortex.

While what’s projected below (troposphere) could and IT IS A ‘COULD’ RATHER THAN WILL eventually leads to significant change above (stratosphere), this is looking more towards later February. So, let’s leave the prospects of a major SSW/vortex split there for now…

However, the evolution within the 500mb pattern could well lead to interesting times in the nearer term. End of week 1 into 2 of Feb.

While the opening week looks relatively unexciting, later next week becomes more intriguing with heights building northwards over Europe potentially presenting a return easterly flow underneath.

The latest GFS ensemble suggests a cooling trend through the upcoming 16 days as heights rise north.

2m temp anomalies

IF the above does indeed develop, the question becomes… what follows into the mid to 2nd half of February. Could this setup continue or do we see a shift perhaps towards the Scandi high backing to Greenland given what’s happening up above?

Modelling suggests this to be the case.

AO trending deeply negative…

My hunch is the potential for the trend to hold cold and easterly between 7/8th and 20/25th Feb.

The CFSv2 for the month of February shows blocking over Scandinavia and while the temp anomaly is warmer than average, I believe we are leaning colder than average for much of central and southern Europe with extention back to UK & Ireland with mean flow out of the east.

GFS ensemble 2m temp anomaly next 30 days.

ECMWF extended next 30 day temp anomaly

There’s possibility of less cold or 20th through 28th but I’m not quite sure how anchored this Scandi high becomes and the type of synoptic setup underneath which could disrupt the flow underneath.

The Verdict

I believe February Is Likely To Be Average To Below Average for Both Temperature & Precipitation For Central & Western Europe Including UK & Ireland…

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