Heavy showers and storms will start to develop on Friday, in central southern England, the Midlands, parts of Wales and especially south-west England.
Gusty winds and hail may accompany the downpours, with the possibility of local flash flooding.
Later in the day, the storms are expected to fade. However, another spell of storms is forecast to reach the south coast of England in the early hours of Saturday, with more downpours spreading across England and Wales throughout the day.
On both days, the thunderstorms will be hit or miss, meaning that some locations will escape them altogether. However, where they do occur, as much as 50mm (2in) of rain could fall.
Sunday is also forecast to bring heavy showers, especially to southern parts of the UK, with more rain expected in the days following.
Not everywhere will experience bad weather, however.
Throughout the weekend and into early next week, Scotland, Northern Ireland and areas around the Irish Sea are expected to experience drier and calmer conditions.
There will be plenty of sunshine and pleasant temperatures. However, make the most of it, as it will not be long before the autumn chill arrives.