Hospitals across south Wales say the icy conditions are sending admissions to accident and emergency units through the roof.
The Abertawe Bro Morgannwg Trust, covering Swansea to Bridgend, says it has been dealing with a constant stream of fall injuries.
It is urging people not to venture out in the ice, especially the elderly.
The Welsh Ambulance Service is asking the public to only contact 999 if absolutely necessary.
Patients are being warned there will potentially be long delays in emergency vehicles getting to people.
The ambulance service said it was still encountering difficulties in maintaining normal service for "routine patient transport" across parts of Wales.
The weather has forced Prince Charles hospital in Merthyr Tydfil to cancel outpatient appointments.
"We're very, very busy at the moment," said Swansea A&E consultant Mike McCabe.
The message is for the public to be careful on the ice and not make unnecessary journeys
Dr Kirsty Dixon-Jardine
Princess of Wales Hospital, Bridgend
"The icy conditions are meaning a high number of falls and broken bones. We've seen many elderly people who have ventured outside and had a fall.
"I can't stress enough that the more elderly and frail should avoid unnecessary trips in such hazardous conditions.
"Even on the driveways and pavements near to home there are the same dangers.
"We need younger family and friends to do their bit and keep a close eye on their loved ones."
Dr Kirsty Dixon-Jardine, at the Princess of Wales Hospital emergency department painted a similar picture.
"We've seen a number of broken bones and injuries from outdoor falls.
"Of course, the message is for the public to be careful on the ice and not make unnecessary journeys."
Hospital staff are also urging the public to use all the health services available - not just A & E units.
Mr McCabe added: "For more minor injuries we have the GP-led minor injuries unit at Singleton Hospital, which has local doctors and emergency nurses available for more routine medical complaints and cuts and scrapes."
He said a local accident centre was also running at Neath Port Talbot Hospital, and urged people with other non-urgent medical problems to contact their GP services first.
However, the cold snap is also continuing to affect some other hospital services, with Prince Charles Hospital in Merthyr cancelling all outpatient appointments for Thursday.
Hospitals are urging the public to make use of all available health services
The Cwm Taf Local Health Board says Aberdare General and Mountain Ash Hospitals have also been forced to cancel rountine appointments.
It said patients will be contacted shortly with alternative dates.
The Diabetic Retinopathy Screening Service for Wales has also cancelled all screening clinics in mid Wales, south Wales and west Wales.
The Newport-based Aneurin Bevan health board appealed for visitors with symptoms of diarrhoea and vomiting within the last 48 hours not to come into hospitals.
On admissions, hospitals were "busy but coping".
A spokesman added: "We are experiencing the usual seasonal surge in diarrhoea and vomiting (D&V) cases, although we still have a few wards affected things have settled now."
However, in north Wales, routine operations and outpatient clinics at Ysbyty Gwynedd in Bangor, Wrexham Maelor Hospital and Ysbyty Glan Clwyd at Bodelwyddan are returning after cancellations on Wednesday.
The Welsh Ambulance Service