More than 800 people in Essex were taken to hospital last weekend as the soaring temperatures took their toll.
A total of 1,949 calls were made to the East of England Ambulance Service - the most in one weekend since January. Some 1,074 were received on the Saturday
Nicholas Jones, manager for one of EEAST's control rooms, said: "We saw a particularly large volume of calls on Saturday, taking more than 700 calls extra compared to the average day."
"We do tend to experience peaks in calls due to extreme weather such as the heat we saw at the weekend, and we'd ask people to take a moment to familiarise themselves with our safety advice, in order to keep their families safe this summer."
The ambulance service praised the work of its staff during the heat wave weekend.
Chief executive Dr Anthony Marsh said: "I'd like to say a huge thank you to everyone for their efforts over the weekend: from our call handlers, to our dispatchers, to all of the crews working on the road, and of course our volunteers."
Emergency 999 calls should only be made for life-threatening emergencies such as strokes, chest-pain, breathing difficulties and serious bleeding.
Other options are available during the week and at weekends, such as out-of-hours GPs and the pharmacist. Ring 111 for health advice at any time of the day or night.
To find out more about EEAST's summer safety advice, visit www.eastamb.nhs.uk or use #999summer on Twitter.
