BBC monthly outlook
Summary
Unsettled at first but turning drier and colder
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Wednesday 27 January – Sunday 31 January
Milder but wetter end of the week for most
The first half of this week was marked by persistent and widespread cold across the country with very sharp frosts and a lot of snow for southern England as well. An Atlantic weather system pushing into the UK on Wednesday will bring a return of the milder sub-tropical air from the Atlantic and bring an end to the frosty start of the week.
Through the rest of January, the weather will continue to be warmer than normal for the time of year but also very unsettled with frequent bands of rain, heavy in places, and some stronger winds at times. As fronts sweep across the country, hills in northern areas will also see some heavy snow at times.
This weekend will continue the unsettled trend but there is some uncertainty on the strength of a low pressure system expected on Sunday. At the moment there are some signals for a sharp frost on Saturday night followed by a potential for some wintry weather on Sunday, but this is reliant on the front moving in at the correct time. If it is a bit too late or a bit too early, the lowland wintry weather is not likely and instead we will just see heavy rain with snow staying over hills.
In short, it will be an unsettled last few days of January with a potentially cold and wintry final day of the month.
Monday 1 February – Sunday 7 February
Changeable weather with a chance of storms
For the first week of February, the weather pattern over Europe will be largely unchanged from late January, at least on a large scale. The low pressure track will continue to send Atlantic weather systems into the UK from the west and southwest making for a changeable week. There will be mild, wet, and windy spells mixed with drier, colder snaps with sharp frosts along with a slight chance of some wintry weather even to low levels at times.
High pressure is expected to build over Greenland and northern Europe in early February, strengthening as we head deeper into the month. This will tend to push the low pressure track further south into the Mediterranean Sea. It will be a slow process though and likely not happen until a bit later in the month. However, there will be plenty of cold air nearby to the north and northeast that will become increasingly widespread.
The cold snaps in early-February may tend to last a few more days compared to late-January. As the low pressure systems move in from the sub-tropical Atlantic, they will be able to tap into some warmer air to give them a bit more energy. There is a chance that we can see a few stronger winter storms push through bringing some significant winds or rain.
Confidence is pretty high overall for early February for Europe, but for the UK it is a bit lower as we are on the boundary between two different airmasses. The difference between the colder and warmer airmasses is around 10 Celsius so minor shifts could lead to some large swings in the expected temperature for a given day.
Monday 8 February – Sunday 21 February
Gradually turning drier but colder
For the second and third weeks of February, we will likely see a gradual pattern shift away from the more unsettled and changeable weather of January to a drier, colder picture. This is because the high pressure system in Greenland from early February will strengthen enough to eventually push lows into southern Europe, so Spain and Italy will get all the wet and windy weather.
For the UK, the colder airmass will move in from the north and bring temperatures consistently below average. This will also be a drier airmass so precipitation will be less frequent, but there will be a growing risk of lowland snow from any showers that do manage to develop. This will be a gradual change though, likely taking place over several days through mid-February, so there will still be some wet, windy, and mild days at first. By the third week of February and beyond, the colder and drier pattern looks to be more dominant. The colder airmass will help create some sharp frosts overnight for much of the country.
Despite the days growing longer as we head to the end of meteorological winter, late-February could well end up being colder than late-January as airmasses continue to shift around.
Confidence for middle and late February's weather is still rather low, as there is a lot riding on the exact strength of the Greenland high which computer models are currently doing a pretty poor job of forecasting.
Further ahead
We will continue to keep a close eye on the factors leading to the development of high pressure in Greenland, as this will be the main driver of cold weather in February.
https://www.bbc.co.uk/weather/outlook