Surprised to learn from MeteoGroup spokeswoman in 'More or Less' (BBC Fri pm) that '40% chance of rain at 2 pm' means for the hours BEFORE 2 pm. Less surprising is that '40%' means that in 4 out of 10 years the synoptics would lead to rain at the given location.

BBC monthly outlook

Saturday 26 May—Sunday 3 June

Getting warmer but with the risk of thunderstorms.

Scotland looks likely to have the best of the weather this weekend with a lot of sunshine and with most places staying largely dry. Low cloud could linger on some eastern coasts though. For the rest of the UK there will be some warm sunshine, but the further south and west you go, the more likely you are to see showers, rain and probably some thunderstorms. Some heavy and thundery downpours are expected on this weekend, mainly over southern and western England and Wales, with Sunday looking like the stormiest day. It will be a warm weekend with temperatures expected to peak around the mid-twenties Celsius, perhaps locally more.

Bank Holiday Monday also looks to be a mixed day with showers and rain reaching further north, but the far north of Scotland should remain dry. It will be a warm day, but it doesn't look quite as warm as we were thinking a few days ago. This is because it looks cloudier on Monday than previously thought, and the lack of Sunshine should keep it a bit cooler. However, it will feel very warm and humid.

For the rest of next week, as we head into the start of June and meteorological summer begins, looks a little bit messy. High pressure is expected to remain close to the UK, so there are should be some dry and sunny weather. However, there are also indications of low pressure systems moving around across north-west Europe, bringing some more unsettled weather at times, so there will be a chance of showers through next week and a few more thunderstorms cannot be ruled out. Although temperatures should become a little cooler by the second half of the week it will probably still be warmer than normal for the time of year in many areas.

Monday 4 June—Sunday 10 June

Cooling off and becoming unsettled.

High pressure is likely to be nearby at first, probably to the north-west of the UK, although as we've seen that doesn't necessarily mean fine and dry weather for all areas. There will be the chance of some showers or rain, particularly in areas further from the high pressure system. However, it should be a little warmer than normal and probably a little drier across the country as a whole. Towards the end of the week there will be a chance of high pressure weakening and low pressure having more of an influence. There is quite a lot of uncertainty at this stage, particularly over the timing of any spell of unsettled weather but this has looked like a possibility for the last week or so. There is also some history of spells of unsettled weather in the middle of an otherwise fine and settled June - something similar happened in 2006 and 2013. Even so, there are only limited indications of significantly wetter and / or windier weather than is normal so we're not expecting a washout.

Monday 11 June—Sunday 24 June

High pressure returns for the second half of June?

If the weather becomes unsettled, it is likely to remain so for a few days up until the middle of the month. After that, there are indications of a return to drier and more settled weather again, with high pressure probably building across Europe from the south-west for the second half of the month. This is indicated by both weather forecasting models and some global scale weather features, so we are relatively confident that the unsettled spell will be short-lived. One thing that is less certain is whether the high pressure will bring warmer weather again. If it builds to the south of the UK then we'll remain in westerly or perhaps north-westerly winds, so temperatures would remain near normal. If the ridge builds to our north, or even across the UK then there will be a greater chance of warmer weather, perhaps not too different from some of the weather we've had in May. As always, details are likely to change in the coming week or so.

Next Update

Will high pressure still be likely at the end of the month, and will it mean 'summery' weather for the UK.

https://www.bbc.co.uk/weather/outlook

UK Outlook for Friday 1 Jun 2018 to Sunday 10 Jun 2018:

By the end of the week and during the weekend, there will be a good deal of dry and fine weather around, with sunny spells. However, there is likely to be some mist and low cloud affecting some eastern coastal districts, although with some sunny spells. However, thundery showers continuing on Friday, before dying out on Saturday from the north. Into next week, there will probably be a good deal of dry weather around, with sunny spells. The driest and sunniest conditions likely to be in the north, with the south perhaps cloudier with risk of thundery showers, especially at first, but probably becoming drier and brighter later. After a warm start, temperatures probably falling, but still likely to be above average.

UK Outlook for Monday 11 Jun 2018 to Monday 25 Jun 2018:

Through this whole period signals are mixed and weak, which generally gives low or very low confidence at this stage. On balance, probably more generally changeable than of late, with spells of rain or showers becoming more frequent and widespread at times, especially during the first half of the period. However, all parts of the country are likely to see some settled spells of weather, particularly in the second half of June. Temperatures probably overall near or slightly above normal. However, there is the potential for further very warm spells of weather to develop across the UK, which are more likely to occur later in the month.

https://www.metoffice.gov.uk/public/weather/forecast/gcwyht9w6#?date=2018-05-24%3C/div%3E%3C/div%3E 

BBC website/weather has posted this summary for May:

https://www.bbc.co.uk/weather/feeds/44334336

I'd like to draw your attention to one comment:

Qu: All the home countries have recorded their warmest day of the year this May.

This would seem no-news considering that's probably the case in most years. However, in this case, I seem to remember April had a 29C+ day? Can someone confirm, as in this release, only 28.7 is mentioned for the early BH weekend. Was there a higher temperature somewhere over the Whitsun BH?

UK Outlook for Thursday 7 Jun 2018 to Saturday 16 Jun 2018:

Thursday should see a good deal of fine weather in the north with sunny spells. However, skies are likely to be generally cloudier in central and southern parts with a risk of scattered heavy showers and thunderstorms. Generally very warm for many, with cooling sea breezes on some coasts. Through the second weekend of June, there's a continued risk of thundery showers in parts of the south, although it may become more generally unsettled in the west later that Sunday. Through the rest of this forecast period until the middle of June, more changeable weather is likely with showers or longer spells of rain pushing in from the west, but interspersed with some drier and warmer periods.

UK Outlook for Sunday 17 Jun 2018 to Sunday 1 Jul 2018:

There is low confidence in the forecast at this stage. However, it looks as though the second half of June will probably start changeable with showers or perhaps longer spells of rain, these interspersed with drier periods. While temperatures may be close to or a little above normal for a time, there will be an ongoing risk that warm, humid and perhaps thundery conditions will spread across the UK from the continent. The last week of the month may become more generally settled, with a chance of warmer temperatures and more sunshine for many.

https://www.metoffice.gov.uk/public/weather/forecast/gfjr8524k#?date=2018-05-27 

Summary

Often fine. Less settled around mid-month though

Circulation patterns over Europe can best be described as "sluggish" at the moment, and the UK has been caught in a warm, humid, unsettled pattern with occasional strong thunderstorms. These conditions will become less likely through the first half of June, and a windier and less warm interlude is expected from around the 10th-11th June through mid-month

Saturday 2 June—Sunday 10 June

Drier early next week, maybe a bit wetter later

The UK will remain under the influence of a warm and humid air mass for a few more days. It will stay unsettled but the threat of the sort of strong storms we've seen recently will diminish. That's going to be especially true over the southern UK, but to the north it will be cloudier with a greater chance of showers or thunderstorms, along with low cloud and mist. The first couple of days of the new week will see a change, with regions towards the east coast likely to be cloudy, misty and cooler with the chance of some patchy drizzle but a lot of dry weather. Meanwhile western regions will have occasional sunshine and warmer conditions.

High pressure will remain situated to the east or north-east of the UK through midweek and into the second half of the week while the jet stream remains weak over the Atlantic with amplified northward and southward diversions. This means that up to the 10th at least we're not expecting any active Atlantic systems to come through, so no strong winds or bands of heavy rain. For a couple of days any precipitation looks likely just to be in the form of some fine drizzle here and there, and it'll be warm in many areas with balmy nights.

By the end of the working week and into the weekend, though, north-western regions are likely to have a weakening frontal system edging across to bring some light rain. Meanwhile the south and southeast will have a risk of a thunderstorm just drifting across from the near-continent, although confidence is low on any threat at this stage.

Monday 11 June—Sunday 17 June

Breezier and cooler

Our forecast expectation of a warmer and calmer June than normal does not preclude interludes of windier, wetter and less warm weather, and one such change looks possible for the week of 11th to 17th June. During that time there looks to be the month's greatest chance for low pressure areas from the Atlantic to push in some breezier, cooler and occasionally wet conditions but this would also mean less chance of any thundery outbreaks. Although this is the favoured evolution, forecasting this far ahead comes with increasing uncertainty and we like to look at potential alternative outcomes. At the moment it looks like there is about a 30% probability for the early June high pressure pattern to linger through this week and keep conditions warmer and calmer with more sunshine but also a greater

thunderstorm risk.

Monday 18 June—Sunday 1 July

Summery conditions expected to return

Beyond mid-month, and especially heading through the final third of June, the position looks most likely to flip again - the most likely outcome is for further extensive high pressure areas to return, particularly over the southern half of the UK, bringing a return to longer periods of warm or very warm and dry weather. This is the most likely scenario but northern regions could still get brushed by the Atlantic lows at times, and now the alternate evolution will be a 30% chance of the cooler, unsettled westerly types continuing. As it stands just northern regions could be brushed by Atlantic systems at times.

Next Update

Although confidence is increasing slightly on the expected cooler, windier and more unsettled spell during mid-June, its extent and longevity are questionable and we can take another look at that as we get a bit closer to it.

https://www.bbc.co.uk/weather/outlook 

Um...the Beeb needs a tighter leash; today's headline:

https://www.bbc.co.uk/news/uk-44341030

May 2018 hottest since records began in UK

is not only misleading, but in its bold statement, grammatically, is completely wrong.

Misleading because it refers only to maximum temperatures; a UK average of 17 is hardly worthy of being called hot, hotter or hottest. 

Inaccurate and false because the spin on 'uk' meaning since uk-as-a-not-very-relevant-whole records began, this is the highest known mean max; this is not the same, in pure, simple English, as 'since records began in the UK'.

MetO you should have fought harder for your contract with the Beeb, to ensure science, not sensationalist claptrap, fed the media with meteorological 'truths'. Bah.

Latest week ahead from the BBC gives heavy thundery type showers returning to the south after wednesday and becoming heavier and more frequent next weekend. Further north generally dry.

BRITAIN is about to be thrust back into the furnace as thunderstorms give way to a two-week heatwave heralding the start of a sizzling summer.

https://www.express.co.uk/news/weather/968228/UK-weather-forecast-hot-long-range-forecast-June-2018-Britain-heatwave-Met-Office-summer 

Well that's summer screwed then. Time to dig out the thermals and galoshers.