In a Wanganui winter a lot of older people have pneumonia and flu and become generally unwell. Lack of heating, a lack of GPs and low incomes add to that.
Ambulance callouts are rising steadily every year, Mr Stretton said. "I think people are expecting more and more of the ambulance."
St John gets calls to earaches and toothaches, when it would be cheaper to call a taxi. Less common are road crashes, strokes, poisoning, suicide attempts, burns and bites.
About a quarter of the time ambulances are transferring patients. At weekends there are fewer callouts, but ambulances are often asked to other centres to cover while neighbouring ambulances are away.
"We have resources moving around all the time."
The average emergency callout takes just over an hour, and patient transfers average 75 minutes each.
Emergency calls go to one of three ambulance communications centres. Wanganui calls are handled in Wellington. Communication is critical for speed and efficiency. Ambulances are fitted with radios, global positioning systems (GPS) and also data terminals that can be read on the road. Ambulance officers carry radios and alert hospitals about patients' conditions before they arrive.
The aim is to arrive at calls within the city within eight minutes. A St John subcommittee is looking for a second ambulance centre in the central city or Wanganui East, to make sure that's possible.
"We struggle to do that, simply because Wanganui is such a spread-out city."
Paramedics can easily get stressed. They have to avoid fatigue - difficult in a night shift with 15 callouts. They're also in contact with powerful bugs. If they get sick they are not allowed back to work until they've had 48 hours without symptoms.
They work closely with the Fire Service. Firefighters have first aid training and fire engines carry defibrillators. Firefighters help St John staff at accidents, and with lifting heavy patients.
Police are also in close touch, and call ambulances when someone has overdosed, injured themselves or assaulted someone. They also help by making sure situations are safe for the medics.
Mr Stretton gave the example of a callout to a 16-year-old female who was short of breath.
"The call taker notices the noise of a party in the background, a party where there could be 50 people. In a case like that we would normally notify the police and get them to look first. The ambulance would stay at a safe forward point and not go in until it's declared safe."
Rescue helicopters also work alongside ambulance staff. Rest homes, GPs and Healthline often call ambulances.
Mr Stretton has had his share of tricky situations.
He was choppered to an Ansett Dash 8 aircraft crash in the Tararuas in 1995.
"There were 20-odd patients and two fatalities, lots of injuries and burns and it was a really, really cold morning up on top of the hills," he said.