Both Tauranga and Whakatāne hospitals have reached full capacity and have asked patients to seek advice from their general practitioner or Healthline before going to the hospital.
It has led to an almost six-hour wait for one patient who went to Tauranga Hospital with a referral yesterday.
A woman, who wished to remain anonymous, said she was accompanying a patient and while they were seen by the nurse around 3.30pm, it was 9pm before the doctor was available.
The Bay of Plenty District Health Board released a statement on Facebook last night explaining the hospitals would be extremely busy over the next 24 hours with unprecedented numbers of patients arriving for treatment.
When the Bay of Plenty Times asked what treatment the DHB was referring to, medical director Dr Hugh Lees said a wide range of winter illness was the cause.
"Winter Sundays and Mondays are normally busy in both hospitals. However, last Sunday and Monday we received higher than normal numbers of presentations.
"The reasons for this unprecedented demand was the cumulative effect of patients presenting with a wide range of winter illnesses, not Covid nor the flu. And many of the people coming into our emergency departments were older people with complex health issues, and this resulted in the admission rates from the emergency departments into hospital wards, higher than normal."
Lees said the situation was the result of increased demand on already particularly busy hospitals.
In June, the DHB acknowledged the backlog of surgeries created by the Covid-19 lockdown.
During alert level 4, from March 25 to April 27, the health board deferred 462 elective surgeries and in May, 280 elective surgeries were deferred.
A spokeswoman at the time said it was not possible to give an accurate estimate of how long it would take for the elective surgery backlog to be cleared.
Today, Lees confirmed some elective surgeries had been deferred this week to ease the pressure.
"The BOP DHB has a backlog of elective surgery and while we are continuing to maximise our own theatre capacity and work with private providers to reduce the waiting times for our patients, we have had to defer some elective surgeries to take pressure off the hospitals this week.
"We continue to be in contact with those patients who are experiencing delays and apologise for any inconvenience this creates for our patients."