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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Outbreaks of light rain or drizzle expected around the coast and hills.
Mike and Cynthia from Ystradgynlais flew out to the German city for a weekend away.
Fine and dry at first but becoming largely cloudy with outbreaks of rain or drizzle.