Spring temperatures may have arrived early this year but people still need to be wary of illnesses that have pushed hospitals close to capacity.
Weather analyst Philip Duncan said the weather pattern for the past week had shifted into what looked more like spring than winter with daily highs reaching up to 18C in some parts of the country.
The coldest weather was typically six weeks after the shortest day (June 21) but many parts of the country had had temperatures normally seen in spring.
"I think we are in for an early spring this year," said Mr Duncan.
However, despite the increase in temperatures many hospitals are close to capacity as the number of people with colds and flus starts to increase.
In the Auckland region, laboratory notifications show a sharp increase in influenza cases over the past month, particularly in the past two weeks.
Dr Cathy Pikholz, Medical Officer of Health for the Auckland Regional Public Health Service, said a lot more people were out there with flu who had not been seen.
"We know these notifications are just the tip of the iceberg," she said.
"We strongly encourage people to get vaccinated especially women who are pregnant, very young children, severely overweight people and those with underlying medical conditions."
While the exact numbers of flu-stricken people was not available last night, many of Auckland's hospitals report busy periods believed to be linked to winter illnesses.
Auckland District Health Board spokesman Mark Fenwick said Auckland City and Starship hospitals had both been "pretty full" during the past week.
However, thanks to a winter plan and extra beds being freed up in other areas, there were about 70 more beds than in previous years so the hospital was not having to turn anyone away.
"We are flat out but we are coping."
Mr Fenwick said the hospitals were seeing many people with cold and flu symptoms and urged sick people to see their GP before going to hospital.
Counties Manukau District Health Board spokeswoman Lauren Young said Middlemore Hospital reached capacity on Wednesday, with around 30 people waiting for theatres and up to 300 needing emergency care.
"Our staff are doing an amazing job under immense pressure."
A lot of the patients had influenza and Ms Young said it was not toolate for people to get the flujab, which she strongly advised.
Waitemata District Health Board spokesman Paul Patton said North Shore Hospital had started out quietly at the weekend but had become very busy yesterday. It was expected to be close to capacity last night.
He said many the patients were coming in with "winter-type infections", something that was also affecting many staff.
The Ministry of Health's latest influenza update says cases are increasing around the country.
However, despite cases being on the rise, the overall picture showed fewer cases than in the previous two years.