Wednesday 12 December—Sunday 16 December

Chilly then wet and windy, perhaps with snow.

Wednesday will be a cool day but most central and eastern areas of the UK will be under the influence of high pressure, so it should be a dry day. The west will be cloudier and there will be some outbreaks of rain for parts of Wales and South West England, perhaps also affecting Northern Ireland and Western Scotland. There will be little change to this pattern to end the working week, although western areas should be drier on Thursday and Friday than on Wednesday. It will be colder in all areas with Thursday night looking cold with the chance of a fairly widespread frost. After a relatively settled week we will see a change with more of an Atlantic influence on our weather by the end of the weekend. The transition from one type of weather to the other does look messy.

Whilst we are confident that an Atlantic low pressure system will push rain across the UK on Friday night and during Saturday, the time of arrival of the rain is proving tricky to pin down.  It does look likely that most parts of the country will see some rain before the end of Saturday. As this rain pushes across the country it will meet cold air and there will be a chance of snow. Again, the details are proving elusive, but it is most likely that high ground in the north of the UK will see snow, whilst lower lying sites in the south will more likely see rain. One other point to note is that Saturday looks to be a very windy day for many areas of the country.  Sunday should be brighter and less windy but with showers and rain in some areas. It will feel milder than previous days.

Monday 17 December—Sunday 23 December

Unsettled but mild for the time of year.

The run up to Christmas looks likely to be unsettled but relatively mild. The main driver of the weather will be a low pressure system or systems, which are expected to be centred to the north-west of the UK and Ireland throughout the week. We expect showers and bands of rain to push eastwards across the UK with most areas seeing at least some rain, but with the west generally wettest. It may also become windy at times, again with western areas probably most prone to seeing the windiest weather. 

Winds will be broadly from the south-west which means that we will have relatively mild air across the country for much of the week. Temperatures are expected to be above normal for mid-December and there is a reduced risk of overnight frosts. The above normal temperatures also mean that any snow is likely to be limited to the Scottish mountains.

Monday 24 December—Sunday 6 January

Staying mild with some very wet and windy days.

The most case is that we won't see much change in the weather for the Christmas period. Broadly speaking, the weather is most likely to remain milder than normal for the time of year although temperatures should be nearer to normal than in the run up to Christmas. There will be a chance of showers and longer spells of rain and it could be cold enough in the north of the UK for there to be the chance of some snow, but this will mainly be on high ground in Scotland.

A white Christmas looks pretty unlikely for most parts of the UK. Looking to the start of 2019, we still see low pressure close to the UK, so further unsettled weather is likely. However, there are signs that high pressure will start to build across the Scandinavia and the north-east of Europe. If this happens then there will be a chance that we could see some cooler air pushing in from the east, so there is the potential for some colder weather during January. Details of the high pressure development will need to be firmed up before we can say for sure whether we will get any wintry weather to start the new year.

Next Update

Will there be any change in the chance of a white Christmas? And will cold weather look more or less likely in January?

https://www.bbc.co.uk/weather/outlook