Flash flooding hits Port Talbot, Neath and Baglan
Parts of Port Talbot, Neath and Baglan have been hit by flash flooding.
Mid and West Wales Fire and Rescue Service said parts of the Sandfields estate and Baglan were under about 2ft (61cm) of water.
A spokeswoman said numerous properties were flooded and whole streets had been affected. Firefighters were also called to Olive Street in Aberavon.
Two supermarkets in Neath were closed temporarily but have since reopened.
As Twitter users posted pictures of affected areas, Morrisons manager James Loxdale said: "We had a flash flood after torrential rain and there was some rain coming into the centre of the store.
"We escorted customers through the checkouts and were shut for about 45 minutes.
"We've reopened now and we would like to thank customers for their patience while we cleaned the store up."
He said the rain came through the roof and some of the ceiling tiles came down.
"There was no harm done and nobody was hurt," added Mr Loxdale.
The Wilkinson store in the town was also closed but it is expected to reopen on Saturday.
A spokesperson said there was water on the shop floor but there was no damage.
Tesco was also temporarily closed.
"The store was shut for about an hour earlier today but now it's open and trading as usual," said a spokesperson.
Jonathan Jarvis, 27, who has lived in Neath for 15 years, said it was the worst flooding he had seen in the town.
'Like a river'
"There was lots of lightning and thunder and a 20-minute spell of torrential rain," he said.
"The main road by Victoria Gardens was streaming like a river for a half an hour period.
"I've been living in Neath for about 15 years and I've never seen it that bad."
He said various stores in the town centre were shut for a time, and some remain closed.
"Quite a few shop owners were coming out and seeing what other shops were doing," he added.
"But it came and went quite quickly. About half an hour later all the flood water went down."
Mid and West Wales Fire and Rescue Service said it had seven crews out dealing with flooding incidents at Port Talbot, as well as the town's Sandfields estate, Neath and Briton Ferry.
Crews are said to be pumping water and unblocking drains but have not had to rescue anybody.
Customers at the Charlie's Angels café in Angel Street, Neath, were unable to leave the premises for a time because of the water level.
Firefighters unblocked the drain outside so that the water receded.
Baglan councillor John Tallamy said Heol y Nant in his ward had again been hit by flooding.
"The houses were flooded out last autumn and that's not the first time this has happened," he said.
"There are floods there again but fortunately the Welsh Water pumps were working to full capacity this time so the houses there weren't under threat.
"Baglan has been built up over the years and the infrastructure doesn't cope with this heavy rain that we get."
Bank Holiday traffic along the M4 in south Wales was hit by driving rain, causing treacherous conditions in places.
Surface water and limited visibility led to slow-moving traffic westbound, which was said to be queueing from Junction 37 (Pyle).
Environment Agency Wales had issued a warning to south and mid Wales of possible surface flooding on Friday.
Neath Port Talbot council said there had been no reports yet of damage to homes.
Head of regeneration Gareth Nutt said: "There is flash flooding in Pentwyn in Baglan which is threatening to flood properties.
"Welsh Water and the fire service and council workmen are attending on site to see if they can prevent as much damage as possible.
"There is also flooding in a number of roads in Sandfields and the fire service is pumping water away. There are no reports of actual damage to any properties."
The Met Office had forecast "intense rainfall and slow-moving heavy showers".
South Wales Fire and Rescue have been helping out neighbouring colleagues in Aberavon.