Thunderstorms are set to bring intense downpours to parts of Britain, and weather warnings have been issued indicating that some homes and businesses could be flooded.

The Met Office alert is in place until 10pm on Sunday, and a second alert covers Monday from 11am until 10pm.

The warnings relate to the East Midlands, north-west and south-west England, Wales, the West Midlands, Yorkshire and the Humber.

Torrential rain is possible and as much as 20 to 30mm (0.8 to 1.2in) of rain could fall within an hour, amounting to 40mm in two to three hours. Lightning, hail and gusty winds could also cause some disruption.

Luke Miall, a forecaster at the Met Office, said: “We’ve got some unsettled weather continuing for the next few days. Quite a contrast, really, to what much of this summer has seen across the UK. This is a thunderstorm warning, so we are likely to see some pretty intense downpours developing as the skies brighten up this afternoon. We’ll see some heavy rain which could give the risk of some flash flooding, as well as spray on the roads and some tricky driving conditions considering a lot of people may well be out and about given it’s [at] the height of the school holidays.”

However, the Met Office said that summer was “not finished”; highs of up to 27C (81F) were expected Monday and Wednesday in the south. Forecasters said Thursday would bring more rain, but there would be hotter and drier conditions from Friday in the south and from Sunday in the north.

Another period of hot weather is expected to last through the following week and remain for the bank holiday weekend at the end of August with highs nudging towards 30C.

Marco Petagna, a Met Office forecaster, said: “We’ve been spoilt in recent weeks, but summer isn’t finished. From Friday and for the following week and to the end of the month it looks increasingly settled, with highs into the high 20s in the south.”

The south would be warmest and driest, forecasters said. The north would be less settled, but also have warm, dry, spells.