On Tuesday 366 people arrived, and at 7pm there were 131 being cared for in the department, with many more waiting for care.
Thirty-eight per cent of people arriving at the department needed to be admitted for further treatment and care.
With a range of winter illnesses affecting staffing levels and the number of cases presented, Te Whatu Ora Waitaha Canterbury acting chief medical officer Richard Laing asked people to save the emergency department for emergencies.
"If you're not sure how urgent your condition is, call Healthline for free health advice any time of day or night by calling 0800 611 116.
"If you require urgent care, please present to Canterbury's other Urgent Care facilities, Riccarton Clinic or the 24-Hour Surgery outside of these hours. If it's an emergency, please call 111."
Moorhouse Medical will also have reduced hours for their urgent care facility again this week and will close at 4pm during the week and 2pm at the weekend due to staff sickness.
Dr Laing apologised for people having to wait, saying it was not an ideal situation.
He advised people to look at their 'Stay Well This Winter' booklet or visit their website for information on self-care for colds and fevers that can be treated at home.
"You can also see your local pharmacist for advice on medication and minor health concerns."
Dr Laing also encouraged Cantabrians to make sure they were up to date with their vaccinations and mask up, particularly in crowded indoor spaces, to protect themselves and others.
