Abertawe Bro Morgannwg University Health Board says many of the people it has been treating have cardiac problems or have suffered a stroke. Many are over the age of 85.
The health board says it has brought in extra staff, and put on extra beds, to deal to with its A&E departments being exceptionally busy.
It says most routine operations have been postponed.
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It will be wet and windy this evening and through much of tonight with some heavy rain at times.
Welsh golfing legend Ian Woosnam has set his sights on securing a home victory at the Wales Senior Open in Newport.
It will be a bright start to Saturday, with some sunny spells. However, cloud and rain will reach the far west by late-afternoon.