Chesterfield Royal Hospital says it is experiencing a 'challenging' Easter weekend.
Many people have been admitted with problems as a result of the warm weather.
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A spokesperson for Chesterfield Royal Hospital said: "We've had a challenging Bank Holiday weekend - and our wards are full.
"As well as critically ill patients, we saw lots of people on Sunday suffering from the effects of an unseasonal Easter - with symptoms of dehydration, sunburn and sun stroke. All of these can be avoided with sensible self care.
"With another sunny day on the cards for you, your family and friends to enjoy, here's some advice that will keep everyone safe outdoors and away from our emergency department: wear sunscreen, a hat, sunglasses, drink plenty of water and cover up - especially from lunch time to mid afternoon.
"By following these tips you'll stay sun safe - and allow our emergency department team to focus on acutely ill patients, anyone who's had a serious accident and those with life-threatening conditions.
"Enjoy Easter Monday safe in the sun."