At least three hospitals have declared critical incidents amid a rare red warning for extreme heat and unprecedented June temperatures.
Queen Alexandra Hospital in Portsmouth and Norfolk and Norwich University Hospitals NHS Foundation Trust both announced critical incidents on Wednesday.
University Hospital Southampton followed suit on Thursday afternoon, citing the “significant pressure on our services” caused by the ongoing heatwave.
This comes as the UK experienced its hottest June day on record for the second consecutive day.
The Met Office provisionally confirmed temperatures reached 36.4C at Yeovilton, Somerset, on Thursday afternoon, marking a new high for the month.
The new high surpasses both the previous record set on Wednesday, when temperatures reached 36.1C in Gosport, Hampshire, and the long-standing record for June heat which dates back to the infamous summer of 1976.
Critical incidents can be declared when health and care services are so busy that special measures are needed to restore normal operations and keep patients safe.
Queen Alexandra Hospital said it declared the critical incident after the “failure of several chiller units supporting critical infrastructure during the ongoing heatwave”.
It added that some planned care and appointments have been stood down until the issues are resolved.
In an update on Thursday, the trust said that while the chiller units were up and running, the exceptionally hot weather has meant that cooling down vital infrastructure was taking much longer than normal.
The trust said it has extended the critical incident to allow it to “bring services back online in a safe and controlled way”.
Some planned care and appointments will continue to be stood down until temperatures have been stabilised, it added.
Michelle Stanley, acting chief executive, Portsmouth Hospitals University NHS Trust, said: “Our teams have worked hard to fix the initial issue and our chillers are now back and working.
“However, the extreme heat means the process of cooling key infrastructure is taking longer than hoped.
“With temperatures still high we are working to bring back services in a controlled manner to ensure the safety of our patients and staff.
“We would like to thank all our partners in the region who have stepped in to help during the incident, their support has been greatly appreciated.”
Norfolk and Norwich University Hospitals NHS Foundation Trust (NNUH) said cooling systems in MRI scanners failed and the critical incident was declared.
A mobile unit was received on Thursday and the trust was “working to reappoint all previously 362 cancelled outpatients”.
NNUH chief operating officer Chris Cobb said: “Due to the hot and humid weather, the cooling systems in our MRI scanners within the hospital building and at the Community Diagnostic Centre failed and a critical incident was declared yesterday.
“We have worked tirelessly in the last 24 hours to bring some of the scanners back online.
“This morning we have received a mobile unit and we now have working scanners across the trust including the Community Diagnostic Centre, which we are prioritising for inpatients and patients on suspected cancer two-week waiting lists.
“We are working to reappoint all 362 previously cancelled outpatients, these will be prioritised in order of urgency. Our emergency department and those requiring urgent care are not affected.
“We are working towards contacting all affected patients and we would like to apologise to everyone affected by this incident.
“We recognise the distress this has caused and will endeavour to get everyone rebooked as soon as possible.
“If you have not been contacted by the hospital, please attend your appointment as usual.”
University Hospital Southampton said it has had to cancel a number of planned operations as well as some outpatient appointments.
The hospital said in a statement: “Our priority is patient safety and the welfare of our staff and we are asking for the public’s support during this time.”
