More than an inch of rain could fall in just one hour as thunderstorms lash parts of north and mid Powys, forecasters have warned.

Slow-moving showers and thunderstorms are expected to develop on Sunday afternoon, with 20-30mm of rain due to hit.

Hail and lightning strikes may also occur, with people warned to expect possible flooding, travel delays and power cuts.

The Met Office has issued a yellow warning from midday until 8pm across much of the north east of Wales and central and northern England.

The warning is in place across areas of Montgomeryshire and Radnorshire, including Newtown, Llanidloes, Knighton, Presteigne, Welshpool, Llanfyllin, Llanfair Caereinion and the Urdd Eisteddfod maes at Mathrafal Farm near Meifod.

Forecaster Kathryn Chalk said: “There could be some disruption, especially for people travelling or out trying to enjoy the bank holiday weekend.

“So I’d say definitely keep an eye out on that. Some southern areas of England may also see a few heavy downpours, perhaps even the odd rumble of thunder as well.”

She added: “It’s just a more unsettled weather regime where the air’s unstable and with more heating in the land it helps develop a storm.”

Saturday was dry and warm for many.

A mix of “sunshine and showers” will be the case for many on bank holiday Monday, with drier conditions possible in parts of Wales, Northern Ireland and south-west England in the afternoon.