BBC monthly outlook
Summary
April looking dry, mild, and sunny. Rain in May
_________________________________
Wednesday 15 April – Sunday 19 April
Wetter, mild in the south. Dry, cool in the north
For the second half of this week, a low pressure system will slowly drift into south west England from the Bay of Biscay. This will bring some showers, heavy or thundery in places, but also some milder air. Thursday and Friday will see showers more widely across southern England and Wales, with temperatures climbing to a little above average, but not nearly as warm as the Easter holiday weekend. Further north, high pressure to the north near Shetland will keep things fine and dry, although the milder air will not reach this far, so temperatures will stay just below normal.
Over the weekend, the low pressure system in the south will linger but begin to slowly drift into France, so a wet, cloudy, and unsettled weekend is in store for most places south of Birmingham, but especially in the southwest. There will be some dry spells mixed in to due to the showery nature of the rain. However, the closer to France the low gets, the less mild air will reach southern England, so by the end of the weekend temperatures across the country are likely to be near or a bit below normal. High pressure will continue to keep things dry for the north, and a ridge will extend further south beginning Sunday, so drier weather is expected in the west too.
Monday 20 April – Sunday 26 April
Very dry but cooler than normal
High pressure from the north will continue to influence the weather for the final full week of April. This will keep things very dry for most of the country, but in particular the northern half which will be nearer to the high. However, a cooler northeast wind will persist through the week, so temperatures everywhere will tend to run slightly below normal. This will be most pronounced in the east and north. The main exception to the dryness will be in the south, where a nearby low will potentially bring some early-week showers.
However, this is only a risk at the moment, and we expect conditions to be mostly dry even along the south coast. Confidence is high with good agreement in the computer models, but there is perhaps a 25% chance that we see some wetter weather in the south through the first half of the week. Rain would mainly be confined to south of the M4 corridor.
Monday 27 April – Sunday 10 May
Drier for a time but rain returns in May
For the end of April and start of May, the high pressure to the north will likely drift north and west, heading for Greenland and Iceland. This will lead to a gradual shift in the pattern from a dry, sunny, calm outlook to some wetter and windier weather. Low pressure tracks will begin to creep in from the southwest via the Bay of Biscay, bringing some spells of rain and winds to most of the country. With the high pressure nearby, this will likely lead to some lengthy dry spells between weather fronts, especially for the northern half of the country. Temperatures will still tend to be below normal as well.
Heading into the first full week of May, low pressure should become more established over the UK with wetter and windier weather for all. This may lead to some slow-moving fronts overhead that tend to keep things very wet for some places. Temperatures will be a bit nearer to normal, but likely still on the cooler side. Warm fronts will bring milder air into Europe, but this will likely struggle to reach into the UK except for perhaps one or two brief warmer days. Confidence is medium for this range with some uncertainty on the intensity of high pressure and the amount of unsettled weather. However, there aren't too many encouraging signs for a warmer-than-normal outlook.
Further ahead
More on May's weather and how the final month of spring is shaping-up.
https://www.bbc.co.uk/weather/outlook