Weather warnings have been issued and there is a chance that homes and businesses could be flooded.
The Met Office alert is in place until 10pm on Sunday night, and a second warning is in place from 11am until 10pm on Monday.
Areas covered by the warnings include Yorkshire and Humber.
Torrential rain is possible and as much as 20 to 30mm of rain could fall in an hour, or 40mm in two to three hours.
Lightning, hail and gusty winds may also result in 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."
Mr Miall added: "This is a thunderstorm warning so we are likely to see some pretty intense downpours developing as the skies brighten up really this afternoon.
"With that we'll see some heavy rain which could give the risk of some flash flooding, as well as the risk of spray on the roads, and some tricky driving conditions considering a lot of people may well be out and about given it's the weekend in the height of the school holidays as well."