There are thunderstorm warnings for the whole of Wales on Saturday and Sunday, but forecasting what areas will be affected is notoriously difficult. The Met Office has a yellow alert in place today between 2pm and 9pm, and tomorrow between noon and 9pm.
They say that high temperatures will "trigger" torrential and thundery rain showers across the country although some parts may not see any rain at all. Its weather maps, reproduced below, give their best estimate of where the thunder will be.
The area of high pressure which has been responsible for the last couple of weeks of settled weather for much of the UK has drifted away towards Scandinavia, allowing a plume of warmer, humid air from the south to influence the weekend weather for much of the UK.
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Temperatures started to climb yesterday as the warmer air pushes in from the south, with the Met Office saying it will bring with it the chance of some evening and overnight showers in southern Wales.
As this warmer air pushes further north and east through the weekend, temperatures will rise triggering widespread thundery showers by Saturday afternoon and again on Sunday.
These will bring the chance of hail and gusty winds for some places, as well as torrential downpours for a few. This will be the first meaningful rainfall for many places across the UK for several weeks. It hasn't rained in some parts of Wales since May 8.
But it can be really difficult to predict exactly where the thunderstorms are going to hit and many places will either miss the worst of any thunderstorms, some staying dry altogether, just a few locations catching the intense downpours.
Here are the current Met Office weather maps taken just after 9am on Saturday (June 10):
This is how Saturday is looking:
The first area to see any thunder and lightning is expected to be in the north east of Wales at around 3pm today
It will continue in isolated patches around the north east of the nation as the afternoon progresses
By 5pm the thunder and lightning is a bit more widespread. The Met Office map as yet does not show any in south Wales. However the BBC's forecast is slightly different and does show some thunderstorms in the Cardiff area at around 6pm.
The Met Office map continues similarly into the evening with isolated pockets of thunder and lightning
This is how Sunday is looking:
Sunday will see a similar picture with largely fine, if slightly cloudy weather, in most areas and some pockets of thunderstorms.
The Met Office maps show more of the unpredictable weather in south east Wales on Sunday in the early afternoon
The thunderstorms are also likely to hit parts of mid Wales on Sunday
And the unpredictable weather continues into the evening, interspersed with clear, sunny spells
There are still some rain and thunderstorms around on Monday
But Tuesday is looking scorching
Met Office chief meteorologist Frank Saunders, says: “Temperatures will increase into the weekend with a peak of 31°C expected on Saturday in central and southeast England. As the heat builds from the south, thundery showers will develop through Saturday afternoon and while not everyone in the warning area will see the heaviest showers, or even any rain at all, some will bring heavy thundery downpours.
"With intense showers there is a risk of surface water flooding which could cause some disruption – the very dry, baked ground may not help in that respect.”
The Met Office says that the signals for next week indicate the risk of thundery downpours will continue at first for some with temperatures likely to remain above average.
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