Forecasters have warned that thunderstorms and heavy downpours may cause flooding and travel disruption on bank holiday Monday.
The Met Office has issued yellow weather warnings for parts of central and southern Scotland, Wales and parts of England on May 6.
It warns that spray and sudden flooding may create difficult driving conditions, with a small chance that homes and businesses could be flooded quickly.
Forecasters said there is a small chance of fast flowing or deep floodwater causing danger to life, while power cuts are also possible and lightning strikes could damage buildings.
A warning covering part of Scotland, northern and central England and Wales is in force between 1pm and 9pm on Monday while one covering London, south-east and part of south-west England is valid between midday and 9pm.
Later in the week the weather is expected to become more settled and temperatures will climb towards the weekend, possibly reaching as high as 23C or 24C in the south by Friday into Saturday and the high teens in Scotland.
Met Office forecaster Craig Snell said: “On Tuesday much of the UK should be dry with a mixture of cloud and sunshine, though probably cloudiest across Scotland.
“Going beyond Tuesday there will be much drier weather for much of the UK and it improves apart from the very far north and Northern Ireland.
“Away from those areas it is generally a dry picture going towards the weekend and on Friday into Saturday we are likely to see temperatures climb probably to 23C or 24C in the south.
“There will be quite warm temperatures for much of the UK, above where they should be for the time of year.
“It will not be wall-to-wall sunshine but the weather will be much more settled.”
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