Yorkshire Ambulance Service had warned they warned it could be overwhelmed on Saturday and Sunday, when wintry weather hit the region.
It said the most serious calls were up almost 30% on last year.
Dr David Macklin, director of operations at the ambulance service, said extra staff and volunteers were drafted in to cope with the demand.
He said compared with 2013, there were over 7,000 more calls to the NHS non-emergency number 111.
The ambulance service covers about 6,000 square miles across the Yorkshire and Humber region, and serves more than five million people.
It said before Christmas it was "very busy" and predicted that because GP practices and NHS services closed over Christmas, they would get "an even higher volume of calls for seasonal illnesses and incidents".
According to the ambulance service:
Dr Macklin said the increase in 999 calls was likely to last into the early part of next year.
Ambulance bosses in Yorkshire have said there were "unprecedented" call levels over the weekend after Christmas.