Damaging storms and high winds are forecast for parts of Western Australia's southeast while to the north, the Pilbara coast has been placed under flood watch.
A cold front moving across from South Australia is likely to deliver the wild weather on Sunday afternoon before easing into Monday morning, the Bureau of Meteorology says.
While the storm winds are expected to average between 50 and 60km/h, most concern is for stronger gusts in excess of 90km/h.
Towns in the firing line along the state's southern coastal strip include Balladonia, Eyre, Forrest, Israelite Bay, Rawlinna and the SA border community of Eucla.
Residents have been warned to find safe shelter away from trees, powerlines, stormwater drains and streams, and to stay inside away from windows, unplug electrical appliances and avoid using landline phones.
Some roads are also likely to be closed.
Heavy rainfall is meanwhile expected in parts of the Pilbara during Sunday into Monday as a cloudband and surface trough move east during the day.
The bureau says catchments are gradually becoming soaked as a result of heavy downpours in the 24 hours to 9am on Sunday and more rain is likely inland and to the north during the day.
Up to 200mm is forecast over the flood watch area, while a further 100 to 150mm is possible on Monday and moderate-to-heavy falls will continue on Tuesday.
Flooding of low-lying areas and river level rises are expected.
Many roads and possibly primary and secondary highways are likely to be affected and some communities may become isolated.
Australian Associated Press
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