The first aid organisation always experiences a surge in demand for its services during the holidays as out-of-town visitors flock to Upper Clutha holiday hot spots.
The increased demands also coincide with a time when the organisation's staffing rosters are stretched as local volunteers also take holidays.
St John Wanaka manager Barbara Roxburgh said ambulance crews attended 43 medical incidents in the four days from New Year's Eve, as well as manning events such as concerts, sporting fixtures and the Wanaka Rodeo.
"We've coped - as we always do. But it's meant a lot of our volunteers have done multiple shifts, which is never ideal."
About 95% of the emergency response incidents were for injuries sustained by visitors to the district, Mrs Roxburgh said.
New Year's Eve and January 1 were particularly busy for the two ambulance crews rostered on, with 30 first aid callouts - predominantly to treat young, alcohol-affected visitors.
Ambulance officer Helen Rule said the injuries sustained by youths were often "a result of their social behaviour landing them in a bit of strife".
St John Wanaka usually has up to 25 volunteers providing 24-hour response crews - split in two 12-hour shifts - but was reduced to an available staff of 10 people to cover the New Year period and through January, Ms Rule said.
The period coincides with a time when the Upper Clutha population almost doubles, leaving ambulance staff "flat out" when responding to incidents, Ms Rule said.
"We had six callouts yesterday and while that may not sound like much, five of them were P-ones [priority one].
Three of them happened within two hours of each other," she said.
A priority one callout is code for a "life-threatening situation" and is the only time when ambulance crews respond with sirens and lights when travelling to an incident.
Volunteers have shouldered a "heavy workload" recently as St John Wanaka tried hard to ensure they always had two ambulance response teams available for incidents, Ms Rule said.
