Forecasters are warning of freezing temperatures this week as England is hit by a cold snap.
The Met Office said there was an 80% chance of "severe cold weather" between Monday morning and Thursday, with snow in some places and icy conditions elsewhere.
A Met Office forecaster said: "This weather could increase the health risks to vulnerable patients and disrupt the delivery of services.
"Please refer to the national Cold Weather Plan and your Trust's emergency plan for appropriate preventive action."
He said the cold and snowy weather would start in the west, making its way eastward in the next few days, although any snow is expected to be limited to higher ground.
"Outbreaks of rain, sleet and snow across southwest England will edge across parts of the west Midlands and central-southern England later today and through tomorrow," he said.
"Snow accumulations are expected but these should be mostly over higher ground.
"Elsewhere, cold and rather cloudy today and tomorrow with some persistent fog/freezing fog patches and a few wintry showers around the east coast.
"Becoming more settled and remaining cold from Tuesday onwards with widespread overnight frosts and a bitter easterly wind.
"Most areas will be dry although a few wintry showers will move in from the east at times."
However, he warned the lowest temperatures would strike London and the south east on Wednesday and Thursday.
The forecaster added: "Turning colder on Wednesday and Thursday, especially across eastern and south-eastern England, with daytime temperatures struggling to rise above zero."