PEOPLE in WA's north are on alert for possible flooding and wild conditions as Cyclone Narelle is upgraded to a category five storm.

The latest update from WA's Department of Fire and Emergency services, issued this morning, says people in Mardie, Onslow, Exmouth and Coral Bay need to prepare for dangerous weather and keep updated with cyclone information.

Cyclone Narelle is estimated to be 445km northwest of Exmouth and 730km north to northwest of Carnarvon and is moving southwest at 10km/h.

Winds of up to 100km/h could develop in coastal areas between Mardie and Exmouth today and then extend south to Cape Cuvier.

Residents in communities to be affected by the storm are advised to get ready for dangerous weather by preparing their homes, ensuring their family knows what to do and checking an emergency kit is complete.