Across the country tens of thousands of non-urgent NHS operations and procedures may be deferred until 31st January.
It came as hospital bosses across the region pleaded with patients to stay away from bursting A&E departments and delayed operations in a bid to free up beds and frontline staff.
"I know it's hard, I know it's frustrating, I know it's disappointing for people, and I apologise".
Mrs May rejected claims that the NHS is in "crisis" saying the health service is better prepared "than ever before" during a visit to Wokingham yesterday.
In the same week before the year's end, bed occupancy was at 91.7 per cent, the same figures also reveal, well over the 85 per cent level considered safe.
More than 15,600 patients were treated in Northern Ireland's main emergency departments between Christmas Eve and New Year's Day - with almost 1,000 forced to endure waiting times of more than 12 hours.
An emergency medicine consultant at a Midlands hospital, who wished to remain anonymous out of concern for his colleagues, told the BMA consultants from across his trust had offered to help but had been unable, with the entire emergency department full and no room in which to operate.
There were 4,734 emergency patients delayed for more than an hour, soaring from 2,413 people in the week before.
Although the winter crunch is a common problem for the NHS, this year's crisis appears to be among the worst.
Asus Just Combined Three Gaming Monitors Into One: CES2018
This new ROG themed accessory also allows for full rotation (360°) meaning placement easy to get the right positioning for you. Finally, there's the Bezel-Free Kit accessory, which attempts to "visually eliminate the gaps" in a multi-monitor setup.
The Dudley Group NHS Foundation Trust saw 820 ambulances arrive, with 268 waiting for up to an hour and 33 for longer than an hour. Some of the worst waits have lasted up to five hours, ambulance crews said.
Referring to the restrictions on implementing health service reform due to the current political instability, he said: "We need reform, we need transformation".
Figures from NHS England show more than 480,000 people called the service last week, which is a rise of 21% on the previous seven days. Performance data for the week over Christmas is due out today.
New Year's Eve witnessed 12 hospital trusts report 100 per cent bed occupancy, the biggest total for several weeks.
"Given that last winter was one of the most challenging that hospitals had faced for well over a decade, it is worrying that many hospitals are already under significant pressure as they struggle to cope with increasing demand for their services".
Professor John Appleby, chief economist of the Nuffield Trust, said: "The sobering reality is that winter for the NHS has hardly started".
"This is far less than the rate of inflation and clearly less than the service desperately needs". They include deferring all elective surgeries until February, allowing hospitals to open mixed-sex wards, and turning prospective emergency-room patients away if they are not seriously ill.
And remember, for young children, the elderly or those with long-term-health conditions, flu can lead to serious health complications - if you worry you or a loved one may be experiencing these, call NHS 111 for advice or consult your GP.
We need more capacity in the entire health and social care systems which means more hospital beds, more nurses and more doctors.