The Welsh Blood Service say the heatwave means fewer donors are volunteering and stocks have been seriously reduced. It particularly wants O and A negative donors. Tracy Sampson of the Welsh Blood Service says patients are relying on donations.
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Rain clipping the far north through the evening but elsewhere staying dry with some sunny spells.
Public Health Wales figures show 25 more cases of the virus have also been confirmed.
Photos taken on Saturday morning show Roald Dahl Plass strewn with empty beer bottles and discarded canisters of laughing gas.