Abertawe Bro Morgannwg University Health Board says it has seen a high number of emergency admissions, and its A&E departments are extremely busy and under pressure.
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Mainly dry with lengthy clear spells overnight and just a few showers likely, especially in the north and west.
Ysgol Uwchradd Caergybi became the UK's first comprehensive 65 years ago. Academies are now dominant in England, but certainly not in Wales.
Dry for most, but a few showers likely.