Medical staff at emergency departments around the country have been stretched to their limits after record-high patient admissions over the summer.
The medical staff are now worried about what winter will bring as cold and flu season kicks in.
Middlemore's chief medical officer, Dr Vanessa Thornton, said the hospital's emergency department saw almost 330 patients a day on average over summer and medical staff struggled to meet the demand.
"We've had an unprecedented increase in emergency department presentations - we had a 9 percent increase in January. We normally increase our staffing in winter but we had increased levels of nursing and medical staff over the summer period to assist."
Dr Thornton said preparations were already underway but there was concern about how the hospital would cope.
"We are generally concerned about this, in fact, we were just discussing this yesterday at a very senior level, discussing what the demand could be in winter now when we've had such a high demand over the summer period.
"At the back-end needing operations, needing ward beds, needing what ever you need."
Both Wellington and Auckland Hospital emergency departments have been seeing around 200 patients a day, numbers usually seen in the thick of winter.
Waikato District Health Board clinical manager Mary-Anne Spence said patient numbers were the highest they'd ever been.
"Certainly January and February were numbers equivalent to what we were having in the winter, so each year we have a growth in our presentation, but this year was significantly higher."
Nurses were also feeling the pressure.
Pediatric nurse, Kate, was among hundreds of nurses across the country who protested for better pay this month.
At the Middlemore Hospital rally, she said nurses were simply burning out.
"It's quite stressful out there, all across the hospital really. We've seen a lot of nursing burn-out which is leading to more sick leave and we just don't have enough bureau nurses to cover those short-falls on the wards.
"The hospital is under so much strain and we're not even in winter yet."
Deborah Powell, from the Resident Doctors Association, said Middlemore had not anticipated the recent spike in migration to the Auckland region.
"The figures that we had anticipated for 2020 in the Auckland region have come now. That increase has just come earlier than we anticipated and quite frankly, we're not ready for it."
In Europe, the flu season, which was now coming to an end, had been particularly bad.
Dr Powell warned that it could be heading south.
"The flu season in the northern hemisphere [had] three times the number of deaths from the flu in the NHS [national health service] and about a 300 percent increase in hospitalisation.
"This flu bug that's coming down, this strain of flu that's coming down from the northern hemisphere this year, is a bad one."
Dr Powell urged everyone to prepare early and get vaccinated.
