BBC Monthly outlook
Monday 16 May—Sunday 22 May
Dry at first, but wet and windy weather on the way
The working week will get off to a relatively quiet but chilly start. A ridge of high pressure positioned just to the west of the UK will allow winds to become light enough and skies to be clear enough for a touch of grass frost to form across some rural areas early on Monday. Temperatures will recover through the day though, and Monday will be a dry and bright day with the best of the sunshine across southwestern parts of the UK. The cloud will be just about be thick enough for a shower across northern Scotland and eastern coastal parts exposed to the North Sea, but even across these areas, most places will stay dry.
Another fairly chilly night will follow into Tuesday morning. For much of England and eastern parts of Scotland, Tuesday will be another relatively fine day though with dry and bright weather expected in the main. Further west, cloud will thicken on Tuesday afternoon as a band of rain moves in from the Atlantic.
Through the rest of Tuesday and into Wednesday, an Atlantic low will cross the UK, bringing wet conditions to most places for a time, with some strong winds across the south. Expect some heavy, thundery showers to form during Wednesday afternoon.
Thursday and Friday look similarly unsettled with further spells of wet and windy weather for most areas at times. Winds will always tend to be stronger in the south ,and decidedly cool air will never be far from the northern half of Scotland, where a mixture of sunshine and slow moving showers will be most likely.
Even into the weekend, current forecasts suggest that the jet stream will continue to push Atlantic low pressure systems our way, with some wet and windy conditions at times for most. The wet weather will temper the feel of the otherwise fairly average temperatures for the time of year.
Monday 23 May—Sunday 29 May
Just as you start to give up hope...
There is an unusual amount of uncertainty regarding the forecast for this period. However, after an initial spell involving a strong, westerly jet stream driving wet, windy and showery conditions across the UK is the most likely scenario suggested by our forecasting tools and models. Pressure is expected to rise across at least the southern-most parts of the UK as this period progresses. This means that as May draws to a close, any showery and cooler conditions are likely to be pushed further and further towards the northwest of the UK, with drier and warmer conditions moving in from the south. The extent to which the fairer conditions move north will likely remain the forecasting challenge if this forecast theme persists.
Monday 30 May—Sunday 12 June
Staying out for the summer? Perhaps for a start.
The climatological summer starts on 1st June. As is always the case with the longer term forecast, there a significant level of inherent uncertainty. That said, the latest forecast trends by the models lean towards the idea of a reasonably fine start to the month of June, with some relatively fine weather for many parts of the UK, but particularly across the south. Conditions also look as if they will be on the warmer side of average. As the month progresses though, the latest forecast suggestion is that the weather start encroaching from the west again, bringing the threat of some wetter and windier conditions at times. Of course, we will keep you up to date with the forecast for early summer over the coming days and weeks here at the BBC Weather Centre.
Next week
Next week we will firm up on some of the details for the end of May and the all-important start of summer!
http://www.bbc.co.uk/weather/2635167#outlook