BBC monthly outlook
Summary
Settling down after a cool, wet, windy weekend
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Saturday 16 March—Sunday 24 March
Becoming calmer after a windy weekend
The recent spell of very unsettled, wet and windy weather is about to come to an end, but not until after a deep area of low pressure has moved across the UK on Saturday. A ridge of high pressure will start to build in the south from Sunday, and this ridge will remain across the south of the UK for much of next week.
In more detail, a developing low pressure system will move eastwards across the UK on Saturday. The centre of the system will pass across Northern Ireland first, then move across southern Scotland and northern England. This weather system will bring another spell of wet and windy weather to many areas of the UK. Gales are possible in some areas, coupled with widespread, locally heavy rain. Central and northern Scotland should avoid the worst of the winds, but will be likely to see snow, this potentially down to low levels.
The low pressure system will move away on Saturday night and on Sunday, but it will be slow to do so, so Sunday is expected to be a windy day with sunny spells and heavy, blustery showers. Later on Sunday, a ridge of high pressure will start to build in from the west. This will mark the start of a spell of much calmer weather. The ridge will remain across the south of the UK for most of next week, so it will be much drier and calmer than it has been recently, although with occasional rain for some northern parts of the country. However, there could be a brief spell of unsettled weather next weekend. Sunday and Monday will be chilly days and there may be a frost in some areas each night. Temperatures will return to near normal, perhaps locally above normal, next week.
Monday 25 March—Sunday 31 March
Much less wet and windy for all areas
After the often wet and windy start to the month, March does indeed look likely to 'go out like a lamb'. High pressure is expected to remain nearby throughout the last week of March. It is most likely to be centred close to or over the south of the UK, but it may expand northwards at times. The upshot of this is that the southern half of the UK is likely to remain relatively settled and dry with light winds. The north of the country will also have some calm and dry weather, although there could be occasional spells of rain and it may become rather breezy at times. Temperatures will be near or a little above the average for the time of year.
The main alternative pattern for the end of March is that we could see low pressure areas developing over Scandinavia or the North Sea, moving into Central Europe. This would tend to make it breezier and cool for the UK and Ireland, with a chance of frequent showers in the north, these perhaps wintry on hills. However, there is a relatively low chance of this, with March much more likely to end on a relatively dry and settled note.
Monday 1 April—Sunday 14 April
Drier, calmer and a little warmer than normal
The most likely weather pattern for the start of April has high pressure lingering close to the UK. It looks most likely to be near the west of the country, blocking the usual eastwards progression of Atlantic weather systems. As a result, the first couple of weeks of April are most likely to be both drier and less windy than normal for the time of year, although still with a chance of spells of wetter, breezier weather for Scotland. It also looks a little warmer than usual in most areas.
However, as always when forecasting the weather at this range, we tend to see one or more alternate patterns. The main alternative to our expected picture is for the ridge of high pressure to stay further west, which would allow low pressure systems to move close to or just to the east of the UK. This would mean cooler, wetter and windier weather. There is also a chance that the ridge of high pressure will move to the north-east of the UK. This too would result in cooler and breezier weather, but it would remain relatively dry. There is a roughly 60/40% split between our most likely scenario and our two alternatives.
Next Update
Will high pressure cling on into the second half of April, or will we see some more traditional April showers?
https://www.bbc.co.uk/weather/outlook