Napier comes in as a close second sunniest city, with 193 hours of sunshine, according to Niwa.
That compares to the second gloomiest city, Christchurch, on 120 hours.
Data also revealed Hokitika has been the wettest place in the country in 2021.
The town had 196mm of rain by January 19, compared to Nelson and Napier, which are tied for the driest place, with 13mm of rain.
It has been a bleak summer so far in Christchurch.
"People would have felt these long stretches of below-average temperatures over the Christmas period," a MetService meteorologist said.
The South has been battered by thunderstorms, heavy rain and strong gales this week.
It is a similar story in Wellington, where gusts reached 124km/h on Friday.
MetService forecaster Sonja Farmer said the wind could get stronger before settling down again.
2021 sunshine hours and rainfall by location:
• New Plymouth: 198 sunshine hours, 113.8mm of rain.
• Napier: 193 sunshine hours, 13mm of rain.
• Auckland (Western Springs): 186 sunshine hours, 80mm of rain.
• Nelson: 181 sunshine hours, 13mm of rain.
• Gisborne: 178 sunshine hours, 43mm of rain.
• Paraparaumu: 160 sunshine hours, 31mm of rain.
• Hokitika Airport: 150 sunshine hours, 196mm of rain.
• Palmerston North: 148 sunshine hours, 59mm of rain.
• Dunedin: 146 sunshine hours, 116mm of rain.
• Taumarunui: 140 sunshine hours, 84mm of rain.
• Kelburn, Wellington: 139 sunshine hours, 20.8mm of rain.
• Christchurch Airport: 120 sunshine hours, 20mm of rain.
• Ashburton: 115 sunshine hours, 33mm of rain.
• Invercargill: 98 sunshine hours, 108mm of rain.