Clean-up efforts in the Northern Territory have begun as ex-tropical cyclone Lam brings heavy rainfall to Western Australia.

A severe weather warning is still in place for Daly, Gregory and Tanami.

NT Chief Minister Adam Giles on Sunday inspected the hardest-hit island communities with Acting Police Commissioner Reece Kershaw.

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About five thousand residents in Galiwinku on Elcho Island, Gapuwiyak in Arnhem Land, Milingimbi and Ramingining bore the brunt of the category four storm as it carved a path of wreckage through Arnhem Land early on Friday.

The NT government declared a state of emergency in those areas on Saturday, which it said would help with the recovery effort.

As Power and Water Corp crews work to restore services, those in affected areas are urged to boil water from a tap before drinking it until advised that tap water is safe.

Residents are also asked to stay clear of downed powerlines and floodwaters, which may hide sharpe objects, crocodiles, snakes and sewerage.

Ex-cyclone Lam is forecast to move into WA’s Kimberley and North Interior district later on Sunday, bringing heavy rainfall and possible flash flooding.

A severe weather warning has been issued for people in effected areas including those in the towns of Derby, Kuri Bay, Kalumburu, Wyndham and Kununurra.

The Bureau of Meteorology says showers and thunderstorms may produce heavy rainfall that may lead to flash flooding in the regions.

“This is typical weather for this time of the year, but rainfall may be locally heavy and could cause damage to property and make road conditions hazardous,” the bureau says.

– with AAP