People are being urged to use the NHS services responsibly as the hot weather and the junior doctors' strike put stress on the West's hospitals.
When compared to their typical Monday patient load of 350, Great Western Hospital in Swindon reported seeing 560 patients.
For heat-related issues like asthma or hay fever, many people attended.
Junior doctor strikes are making the situation for hospitals even more difficult.
They are wrapping up the strikes earlier than they did during previous industrial action, according to Dr. Emma Coombes of the British Medical Association.
The temperature is so high, and yesterday we saw a few cases of sunstroke.
Both patient and doctor safety are concerns of ours. ".
Members of the British Medical Association have been on strike for 72 hours as of Wednesday morning BST.
The pay dispute has now reached its third strike.
A "significant number of patients," according to Dr. Jon Westbrook, chief medical officer at Great Western Hospital, have been presenting with respiratory problems recently.
When compared to a typical Monday, "we saw 560 patients, as opposed to looking at about 350," he said.
The hospital encourages patients to use Walk-in Center and NHS 111, which are both online and by phone, as alternatives to A&E.
Hospitals have implemented cover, according to Dr. Michael Marsh, Regional Medical Director for NHS England's South West.
However, he acknowledged that with fewer staff, it would be difficult to handle any potential increases in demand for the health system. "The reality is that the work we are seeing relates to just normal conditions, it is not caused by the strike," he said.
The problem is that there is evidence that we face additional difficulties as a result of the extremely hot weather and high pollen count. ".
In spite of the strikes, hospitals are "well prepared to keep services running," according to Dr. Marsh, who also noted that they are "as good a place as we can be."
