The freezing temperatures have put the service under more pressure
South Central Ambulance Service has appealed for people not to dial 999 with non-emergencies as it faces more calls because of the wintry weather.
The service said it had experienced an increased demand in Berkshire, Oxfordshire and Buckinghamshire, due to the freezing temperatures.
Its plea comes after heavy snowfall in Berkshire led to up to four inches (10cm) settling in parts of the county.
The service has 103 ambulances and 43 rapid response vehicles.
A spokeswoman said: "The service, which also provides 999 cover for Hampshire, uses sports utility vehicles [4x4s] to safely navigate through the consequences of adverse weather like floods, ice and snow because the standard response vehicles may experience difficulty in reaching patients under these conditions.
"We are taking longer to get to locations due to the poor driving conditions caused by the weather.
"We would like to ask the public to help us keep ambulances free to respond to emergency calls."
Meanwhile, the AA described Saturday as its busiest day of the year so far.
The breakdown organisation said by 1500 GMT it had attended around 13,000 call-outs.