Ambulance crews are being pushed to "breaking point" following an unprecedented surge in 999 calls.
Almost 1,000 additional emergency calls were made in Devon and Cornwall over a two-week period this month compared with the same time last year.
Crews dealt with 10,134 emergency incidents between March 4 and 17 – a similar level of demand to New Year – compared with 9,148 calls last year.
"It's been like a New Year's Eve every day of the week," said John Oliver of the South Western Ambulance Service Trust (SWAST).
The SWAST blamed the 11% rise in call volumes across the region on the cold weather.
It urged people across the South West to consider other ways of getting health care rather than dialling 999 in the first instance.
But the union Unison claimed the rise was partly because out-of-hours calls were being diverted to the 999 emergency number.
It said ambulance crews had been "run ragged" by a combination of factors including inadequate staff provision.
Simon Newell, Unison South West regional organiser, said: "Resources are being stretched to breaking point. Ambulance crews have been busier every weekend so far in March than they are during the seven busiest hours of the year on New Year's Eve."
He added: "Lives are being put at risk because inexperienced and inadequately trained staff are dispatching more ambulances than are needed and sending them to the wrong places."
Earlier this month Plymouth's Derriford Hospital was on "black" alert, meaning it was under extreme pressure and the Royal Cornwall Hospital's major incident plan was put into action.
The ambulance trust has urged people to only call 999 in "real emergencies". Norma Lane, SWAST director of delivery, said weekends were currently proving "particularly busy."
Mr Oliver added: "Much of it is due to the cold weather which exacerbates respiratory and chest problems for patients with existing medical conditions."
"It's definitely putting a strain on resources. People are working overtime and taking on extra paid shifts. Our priority is to get the right help to the people who need it the most. But we are undoubtedly under pressure.
"There has been short-term dip in the speed of dealing with emergency calls due to finite resources. We're trying to minimise that dip in performance and offer as good a service as possible."
Unions fear ambulance crews will be put under more pressure once a new NHS 111 number for patients with urgent but not life-threatening symptoms is introduced.
The system has been delayed in Devon and Cornwall until May and June respectively, even though it is already being used in other parts of the South West.
