Hallswood Animal Sanctuary, based near Norwich, has issued the plea following the death of a hedgehog due to severe dehydration.
It comes as Norfolk is in its third heatwave of the year, with very little rain.
Large parts of the county are also in a hosepipe ban after record-breaking temperatures of 37C were reached in Lingwood last month.
A spokesman for the centre said: “Please put fresh water out, the wildlife are dying for a drink.
It is currently hoglet season (Image: Hallswood Animal Sancuary)
“Once they are dehydrated, it’s only time before they die.
“The most important thing you can do at present is put fresh water down in your gardens.”
The centre shared the recent case of an older female hedgehog that was found struggling in a garden during the day and died shortly after being brought to the centre.
The hedgehog was “lactating and so dehydrated she drank endlessly, after she had given everything to her young.”
RSPCA East Winch Centre is also currently caring for more than 100 young hedgehogs, with 55 still needing milk feeds.
Like Hallswood Animal Sanctuary, the RSPCA centre is also urging people to help where they can, especially as it is hoglet season.