Pen y Fan visitors told to expect Storey Arms long queues
Walkers have been urged to find alternative routes to Pen y fan this weekend, with road work expected to cause traffic congestion.
Dyfed-Powys Police said resurfacing work on the A470 at Storey Arms will mean slow-moving traffic and queues.
It also urged motorists to park sensibly near Storey Arms, with officers set to look for vehicles causing obstruction.
Sgt Owen Dillion said illegal parking created a danger for pedestrians.
"Motorists should be aware that congestion is highly likely due to the road works and I would ask them to consider if the journey is really necessary or safe," he added.
He also urged motorists to look at alternative routes up to Pen y Fan.
"The area is a national park and much of the Storey Arms section of the A470 is a clearway which means that roadside parking is not permitted," he said.
Motorists were also warned about parking illegally earlier this month.