The Met Office has issued a yellow weather alert for parts of England and Wales on Sunday, as storms, hail and strong winds are expected to hit some areas.
The storms are caused by the warm and humid air that has been present this week.
The weather warning means that there could be some travel disruption and power cuts, as well as flash flooding due to heavy rain.
Some places could see up to 30mm of rain in an hour, which is more than the average rainfall for a whole month.
BBC Weather’s Matt Taylor said that thunderstorms are likely to develop across the UK and Ireland over the weekend, with Northern Ireland’s western half being most at risk on Saturday.
He said that on Sunday, the storms could become more severe and widespread, with lightning, hail, strong winds and flooding posing a threat.
He added that not everyone will experience the storms, as some areas will remain dry and sunny.
The hot weather will also continue, with temperatures reaching up to 29C (84F) in some parts.
However, by Sunday night, the stormy weather could affect more of northern and eastern England, as well as eastern Scotland.
This comes after a week of heatwave conditions in many parts of the UK, which have been linked to climate change.
The high temperatures have also caused water supply issues in Kent and Sussex, where a hosepipe ban was imposed on Friday after record levels of drinking water demand in June.
Up to 4,000 customers have been affected by water shortages or low pressure since Monday