To kick things off, here are some charts - please feel free to add more!

The 6z GFS today starts the new year with a -12:

https://images.meteociel.fr/im/71/26272/90_583UKypk1.GIF 

A milder night follows (-4), then the cold returns... -14 on Friday morning, -15 on Monday morning and another -14 on Tuesday morning. Here's the -15:

https://images.meteociel.fr/im/69/29684/216_583UKkiy4.GIF 

The MetO run takes the prize so far, though, with widespread -18s to -20s:

https://images.meteociel.fr/im/82/10529/ukmohd_uk1_32_150_0mky2.png 

The TWO view (which isn't static, so this chart will change) shows a -22 and, I suspect, a -23 - but there's no key to confirm!

https://www.theweatheroutlook.com/charts/ukguk/00_150_2m_min_temp.png 

Now, we've seen this before and it's not verified, but even so it looks like a spell of negative double digits is likely.

The "Beast" in 2018 had the lowest temperatures since 1987 here, -14.8. That's the target to beat this time around, but I doubt I'll manage it! Maybe you will if you get enough snow? A thick cover is vital for the very lowest temperatures, and anecdotally very cold air aloft is beneficial too. (2017-8 was also noteworthy as the lowest official UK temperature recorded that winter was at Brogdale in Faversham, which of course held the UK's record *high* temperature from 2003 for 16 years.)

This morning's low temperature watch starts with GEFS, which shows a chilly Hogmanay for those in western Scotland - I suspect those "first-footing" won't dawdle on the doorstep! -10s appear by 6 AM, and that sets off a remarkable run of double-digit negatives. We have:

1st Jan: -10 over western Scotland

2nd: -14, Highlands

3rd: -13, multiple areas of Scotland, -10, Northern Ireland, -12 northern England

4th: -12, both sides of the Scottish border, -11, Northern Ireland (and -10 spilling into the Republic of Ireland)

5th: -10, over a small part of northern England

6th: -16, with -15 over multiple parts of Scotland, -10 or below widely, -12 over Northern Ireland

7th: -13, Highlands

8th: -12, Highlands, -10, Northern Ireland

That's exceptional for modern times and would be noteworthy even in previous colder decades. It's no wonder that the wxmaps chart has an area of -8 to -10C *mean* temperatures over Scotland in week 2. That's about as cold as it ever gets on those charts... -5C is rare, and -10 has only appeared once or twice in the 20+ years I've been looking at them.

http://wxmaps.org/pix/temp4.png 

Here's the peak cold from GFS this morning:

https://images.meteociel.fr/im/22/8827/198_583UKwvy0.GIF 

The MetO high-res joins in too, with -12 showing up on the 1st:

https://www.theweatheroutlook.com/charts/ukguk/00_84_2m_min_temp.png 

There are more double-digit negatives on the 2nd, then this on the 3rd - yes, those are some -23s appearing! I suspect there are some even colder than that, but again there's no key for the deep purple so it's hard to say for sure.

https://www.theweatheroutlook.com/charts/ukguk/00_129_2m_min_temp.png 

There are then much smaller areas of -10s or below on the following two nights.

Snowcover plays a major role in nightime lows. Getting some depths could make a big difference, and I'm also hoping that establishing some snow cover in Scotland helps the rest of us by cooling any air advected over it.

Morning of 1st Jan: nothing

2nd Jan: -10, far north England

3rd Jan: -12, still over N England

4th, 5th Jan: nothing

6th Jan: -11 Highlands, -10 N England

7th Jan: -12 Highlands

8th Jan: -13 Highlands

9th Jan: -11 Aberdeenshire

It seems this is related to the change in areas seeing snowfall, and the depth of the same - the really low temperatures start appearing when there's more then 10cm on the ground, it seems.

The MetO model, as seen on this site, has also backed off in terms of the super-low temperatures. It still rustles up a -13 on the morning of the 2nd, -15 late on the 3rd, then -16 on the 6th, all over Scotland rather than further south.

https://www.wetterzentrale.de/en/topkarten.php?map=20&model=gem&var=5&run=0&time=222&lid=OP&h=0&mv=0&tr=3#mapref 

Interesting, the MC view is more detailed but doesn't cover all the UK. There's a -15 lurking over the snowfields!

https://images.meteociel.fr/im/38/27409/gemfr_19_222pkk0.png 

https://www.theweatheroutlook.com/charts2/gem/00_201_uk2mtmp.png 

I think that takes the prize so far today! 😁

The reality? No snow, plenty of rain (Loch Glascarnoch, Altnaharra and Aviemore all reporting rain as of now) and around 2C!

I'll keep a tally going of reported UK minima  over the next few days, starting with:

31st December: Lerwick, -1.5C

1st January: Baltasound, -0.2C.

(That wasn't very impressive, was it? At least today's will be colder, it's currently -5C at Shap, for example).

EDIT : -7.9 at Benson earlier in the night; the above were 0700 hrs observations

That's useful info, and no surprise that there were some stations reporting a fair bit below the official ones! I'd imagine it'll be a similar thing over the next few days.

In a way the UK Met models have tried to build this behaviour in, but obviously the effect is over-exaggerated. The other models seem much more damped and don't display the same extremes. 

https://weather.metoffice.gov.uk/forecast/gfjkvjeuz#?date=2025-01-05 

It is quite chilly up here still before the rain comes in considering itis cloudy. It’s -3°C here in this bit of the city but -7°C at Aberdeen airport currently (and colder more widely inland).

It’s a relatively “mild” -3.2°C in my garden currently, but given that it’s in the city and less than 2 miles from the sea it’s still quite impressive. It’s a shame the next day or so will be less wintry as it would have been a very notable start to the year otherwise.

It's the best time of year for that sort of thing, I'd imagine. Solar input is so low at the moment... and will remain so up there for a while yet. (Even down here, you don't tend to notice a "kick" until February).

The Met Office afternoon update video suggested it'll be a much milder night tonight over Scotland, they had 1C for Aberdeen and that was about as low as it got. It's then Monday night which sees the return of noteworthy lows again - I'd be surprised if we didn't get at least a -5 out of the Highlands tonight though!