Food and water are on the way to people trapped by the worst floods in 50 years around the Western Australian town of Carnarvon, said authorities of Western Australia on Monday.

Carnarvon, about 900km north of Perth and at the mouth of the Gascoyne River, is hit by its worst flood since 1960.

Residents were warned on Saturday to evacuate as torrential rain pounded the region overnight.

An evacuation point was set up at the Carnarvon Civic Center, where at least 80 people stayed overnight.

A Fire and Emergency Services Authority (FESA) spokesman said the river was expected to peak early on Monday.

The river level had risen to 7.7 meters at Nine Mile Bridge by 9p.m. (local time) on Sunday and was expected to rise slowly ahead of the peak of 7.8 to 7.9 meters.

Two consignments of food and water were expected to leave Geraldton, the capital of Western Australia's Mid West, early on Monday, while emergency workers in Carnarvon would audit food and water needs for people isolated in the town and in outlying areas.

On Sunday, 30 people stuck on rooftops at Gascoyne Junction, about 170km inland from Carnarvon, and six more at Meka station, about 510km north of Perth, were flown by helicopter to Carnarvon and most were housed overnight at the civic center.