Buller Health's acute stabilisation unit (ASU) in Westport, known as the hospital, is closed overnight Wednesday due to staff illness.
It was at least the forth time in a month the hospital was closed.
It will be closed from 5.30pm Wednesday to 8.30am Thursday.
Te Whatu Ora asks people with an emergency during this time to call 111 an ask for an ambulance.
"Like everyone else in the community, our staff are susceptible to winter illnesses and when they are unwell, it's important they take time away from work to get well," said Helen Gillespie, Health New Zealand West Coast's Operations Manager - Northern.
"We would like to thank the Westport community for their understanding and apologise for any inconvenience this situation may cause. Please be reassured that if you or a whānau member needs emergency care this is available."
It says St John will continue to provide usual emergency response services and a clinician trained in primary responce in medical emergencies will be on call to support them.
Greymouth's Te Nīkau Hospital, 100km away, will take anyone needing to be admitted.