December weather: Unusually cool start to summer

Temperatures for December 1 have fluctuated for the last decade between as hot as 27C and as cold as 13C. This year was the coolest since 2006. Photo / Doug Sherring

The country has had the coolest start to summer in almost a decade.

Temperatures around the main cities on Monday were well below the median for the past decade, as a southwesterly flow swept through.

"It's unseasonable, but it's not [completely] unusual," MetService forecaster Richard Finnie said.

Temperatures for December 1 have fluctuated for the last decade between as hot as 27C and as cold as 13C. This year was the coolest since 2006.

Auckland and Hamilton started summer with a cool 17C day, while Wellington and Christchurch recorded a chilly 14C.

In 2010, Auckland reached a balmy 25C for the first day of summer while Hamilton was even warmer, recording 27C.

Whereas on December 1, 2006, temperatures only reached 17C in Auckland and Hamilton and 13C in Wellington and Christchurch.

Mr Finnie said the country experienced a southwesterly flow on December 1, 2006, similar to what was moving across the country on Monday.

On the second morning of summer, those in southern parts of New Zealand had to scrape ice off windscreens as Monday's southerly faded out.

WeatherWatch head weather analyst Philip Duncan said warmer westerlies would return tomorrow, bringing warm weather for the weekend and next week.

"The same high that is partially responsible for dredging up this cold air will also give us some sunny, hot days ahead," he said.