Updated 4th December - Covering 11th Dec 2023 - 2nd January 2024
Relative to the 1991-2020 long-term average, this period is forecast to be around 1.5C warmer than average in south-east England, but less than 1C warmer than average in most parts of Scotland, and potentially very close to average in northern Scotland.
It is forecast to be wetter than average in most parts of the UK, despite a fair amount of dry and quiet weather being expected during Week 3. Northern Scotland may see near or slightly below average precipitation overall.
Sunshine totals are likely to be low for most early in the period, but then picking up, and near average sunshine is the most likely overall outcome for most of the UK.
A mild and changeable south-westerly type will dominate the weather for most of this week, with low pressure centred over and to the west of Ireland, bringing spells of wet weather to most of the country. The wettest weather will generally be in western and southern parts of the UK, with a likelihood of it staying relatively dry in northern Scotland. Temperatures will tend to be somewhat above the long-term normal for mid-December, except in northern Scotland, as the warmer air masses pushing in from the south and south-west may struggle to make much progress into northern Scotland. Snowfall is likely to be largely restricted to high ground in Scotland during this week.
There are signs that towards the end of the week, the weather may turn rather less wet and unsettled, with some ridges of high pressure moving in from the south and south-west at times, and merging with an increasingly strong anticyclone over eastern Europe. We will still see low pressure systems and fronts move in from the North Atlantic, with a predominantly west to south-westerly flow over the British Isles, but with the low pressure systems tending to track somewhat further north than earlier in the week, leaving southern areas in particular with substantial drier periods in between the rain belts. Temperatures may fall close to normal towards the end of the week also.
Temperatures are thus forecast to be above the 1991-2020 long-term normal in most regions, probably by 2 to 3C in south-east England, but they may be less than 1C warmer than normal in northern Scotland.
It will be wetter than average in most parts of the UK, particularly the south, due to some heavy and persistent rain often affecting the south early in the week. Northern Scotland is likely to have near or below average rainfall, particularly in the far north-west of Scotland.
Sunshine totals are likely to be below average for most, though they may pick up towards the end of the week. North-west Scotland may have near or slightly above average sunshine.
Some settled spells are expected during this week, especially early on, with potential for a Scandinavian blocking high to feature during the week, although at present it does not look likely that this will bring substantial cold snowy weather in from the east, with Britain most likely to be affected by high pressure and/or southerly winds for most of the time. Nonetheless, temperatures are likely to fall close to the long-term normal during this week with potential for colder than average weather to develop at times, particularly in England and Wales, with some overnight frost and fog patches. There are signs that it will turn more unsettled from the west as we head towards the very end of the week, but there is some uncertainty around the specifics of this. There is a possibility of some snowfalls, chiefly in the north and east, as frontal systems push against the Scandinavian high - at present this only looks around 20-30% likely, but worth keeping an eye on especially due to the resulting potential for some areas to see a white Christmas.
This period is likely to be drier than average for most, with temperatures generally close to the long-term average. Sunshine amounts are somewhat more uncertain, due to the potential for cloudy anticyclones at this time of year, but averaged nationally they will probably be above normal.
This period looks set to become predominantly mild and wet, as low pressure systems push in from the west and the Scandinavian high retreats eastwards into Siberia. It is especially likely to be predominantly mild in the south, but northern areas have potential to see some cold snaps, most likely associated with the Scandinavian high early in the period, and then from polar maritime north-westerlies towards the end of the period. Thus, at present a white Christmas looks unlikely in southern Britain but there is some potential in the northern half of Britain. Generally this period is expected to be somewhat wetter than average, with temperatures around 2C above average in south-east England but less than 1C warmer than average in most parts of Scotland and Northern Ireland. Sunshine amounts are likely to be above average in the east, near or below average in the west.
Monthly weather forecast
The month ahead forecast is written by Ian Simpson and is updated every Monday.