BBC monthly outlook
Summary
Overall, April looks drier and warmer than normal.
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Wednesday 1 April – Sunday 5 April
Cool end to the week but warmer this weekend.
For the second half of this week, high pressure to the west of Ireland will gradually decline and shift westwards into the North Atlantic. As it does this, a low pressure system will deepen north of the UK as it heads southeast into Scandinavia. The result will be a weak cold front that will push south across the UK starting Wednesday and lasting into Thursday. As the front heads further south it will grow weaker, so much of England and Wales will likely stay dry, but Scotland and Northern Ireland will have some bands of rain to contend with.
This is still a cold front as well, even though it's weak, so it will bring in some stronger winds and colder air behind it. Scotland will cool off first with cold air spreading south through Friday. Some scattered wintry showers are likely in northern coasts with some snow for hills in the Northwest Highlands. Strong winds are also likely for Scotland and parts of Northern Ireland and North England on Thursday.
For the end of the week and through the weekend, high pressure will build in again from the west and ease the winds and rain for most. On Saturday and into Sunday as the high slides across the UK, the winds will shift to more southerly. This will bring in some much milder air from the sub-tropical Atlantic. Sunny, warm weather is likely, especially on Sunday, for most of the country this weekend. Scotland and Northern Ireland will likely run a bit cloudier though.
Monday 6 April – Sunday 12 April
Likely mostly dry, but rain chances in the north.
Although the ridge of high pressure is expected to drift eastwards at the start of April, it is likely to start to drift westwards again as we move towards the middle of the month. For the UK, this means that there will likely be more settled weather especially later in the week. However, as the high reaches into the North Atlantic, northwesterly winds may feed some cooler air in from near Iceland. The north and west of the country are most likely to see a few showers and rain at first. Scotland and Northern Ireland will probably end up wettest, with a risk of some rain even into the end of the week. Meanwhile, the further south and east you are across the country, the more likely you are to have drier and calmer weather.
Temperatures are likely to be near or a tad above average in south-eastern parts of the country, and near or perhaps a little below normal in the north and west. Overall confidence is hovering around medium. This is because minor shifts in the location of the high pressure will have some large changes in the expected weather here. If it is more of an extensive feature then expected, and this is most likely in the first half of the week, then more of the country will be relatively dry and calm, but also a bit warmer than average. If the ridge of high pressure is less of a feature, as is possible at the end of the week, then expect wetter and windier weather throughout.
Monday 13 April – Sunday 26 April
Probably drier, less windy than normal.
The middle and end of April will see high pressure centred broadly our west and south-west. This should mean that Atlantic weather systems are stopped from affecting much of the country as they usually would. The result is that we should see a spell of relatively dry weather for most of the country. This doesn't mean completely dry of course - weather systems could creep around the northern side of this high pressure system and bring some rain, this most likely to affect Scotland and Northern Ireland. On the whole, it should be drier than normal for the time of year. The north of the UK is more likely to see windier weather than the south, but it doesn't look like a very windy couple of weeks in most areas.
Finally, on to the temperature forecast. Winds should come broadly from the west or southwest. This should result in some warmer than normal air being pushed across parts of the country at times. As a result, we think it is most likely that temperatures will be above normal for the time of year, especially for the southern half of the country. Whilst that doesn't rule out some cooler spells of weather, it should make any late overnight frosts or wintry showers less likely - even in Scotland.
As always with these longer range forecast, there is a bit of uncertainty. As with earlier in the month, the uncertainty centres around how extensive high pressure is across western Europe. There is a chance that it might be less influential and Atlantic weather systems bring more unsettled, wetter and windier weather to the UK -something perhaps a bit more like typical of mid-to-late April weather?
Further ahead
Although the mild, dry April forecast continues to hold, confidence is still only medium. Will late April end up wetter after all?
https://www.bbc.co.uk/weather/outlook