Weather warning for thunderstorms affecting Wales
The yellow alert from the Met Office covers much of the UK.
Thunderstorm warnings are still in place as up to three inches of rain could fall in parts of the UK on Monday.
The yellow warning was issued over the weekend and another warning will be in place until midnight on Monday covering large areas of the UK - including across Wales.
On Monday, between 30 and 40mm of rain could fall in an hour widely, and in local areas between 60 and 80mm of rain could be seen, potentially sparking flash flooding, the Met Office said.
Marco Petagna, senior operational meteorologist, said the thunderstorms are due to "low pressure sitting over the UK".
He said: "There's a risk of heavy showers which could be thundery in places, especially central and eastern parts of the UK."
Flooding, lightning strikes, travel delays and cancellations are possible and there is also a slight chance of power cuts, Mr Petagna added.
On Sunday, up to 25mm of rain fell in an hour in parts of Dorset, while temperatures reached 30C in the south east.
On Monday the temperatures are set to reach 25C, again in the south east, and it will feel colder towards the north and west, Mr Petagna said.
Tuesday and Wednesday are forecast to see lighter and more scattered showers and sunshine but from Thursday onwards thunderstorms are again expected in the south.