Holidaymakers planning to head to Bremer Bay are being told to delay their plans as a bushfire bears down on the south west townsite.

Key points: The fire has caused campgrounds and roads to be closed and people in the area have been told to leave immediately

The fire has caused campgrounds and roads to be closed and people in the area have been told to leave immediately Total fire bans have been declared across much of Western Australia's south coast

Total fire bans have been declared across much of Western Australia's south coast More than 100 firefighters have been sent to the scene

A Watch and Act alert has been issued for the town of Bremer Bay, on the Western Australia south coast east of Albany, as well as campsites in parts of Bremer Bay and Boxwood Hill in the Shire of Jerramungup.

The fire is threatening an area bounded by Borden-Bremer Bay Road to the north, the Bremer Bay coastline to the east, the coastline to the south and the intersection of Borden-Bremer Bay Road and Gairdner South Road to the west.

The Department of Fire and Emergency Services (DFES) said there was a threat to lives and homes due to a forecast wind change.

DFES Great Southern Superintendent Wayne Green said challenging weather conditions had impacted on the fire's behaviour.

"We've had the spread of the fire in three of four directions," he said.

He said while firefighters had so far reported zero losses, there were still challenging times ahead.

"We've got easterly winds which are going to put pressure on the western flank of the fire, which is critical to us because that's going to head down towards Millers Point campground and down near the Pallinup River," he said.

"If it gets on to the other side of Pallinup River, that's the really inaccessible, nasty terrain, and needless to say there's always some communities tucked away.

"The crews are going very hard at the moment to make sure it doesn't get to that point."

The fire is uncontained and uncontrolled and DFES said to avoid South Coast Highway between Wellstead and Jerramungup because thick smoke was affecting visibility.

Several roads in the area have been closed and a temporary evacuation centre has been set up at the Jerramungup Recreation Centre.

Reef Beach, surrounding sand dunes and nearby camping areas have been closed and are expected to be closed for some time. People camping in the area need to leave immediately.

People planning to camp at Reef Beach and surrounding sites this week have been told to avoid the area and those considering holidaying in Bremer Bay and surrounding camp sites should delay their plans until the area is declared safe.

About 110 firefighters have attended the scene and aerial support has been sent to assist.

Total fire bans have been declared over much of WA's south coast for Saturday, including the shires of Esperance, Denmark, Jerramungup, Ravensthorpe, Albany and Plantagenet.