Sizzling festive season ahead - La Nina's gift to New Zealand

Kiwis across the country can expect warm, dry weather on the big day. Photo / Doug Sherring

Never mind "ho, ho, ho". This Christmas is shaping up to be hot, hot, hot. The festive season will be warm, settled and dry, thanks to the La Nina weather system.

Kiwis in most parts of the country can plan for a barbecue in the backyard on the big day, with warm weather likely in most parts of the country.

Niwa principal climate scientist James Renwick said he hoped Christmas would be "a nice day in most places". He said the latter half of December should be fairly dry, settled and sunny.

Niwa's seasonal climate outlook from now until February finds the temperature is likely to be near or above average in most places.

"In a La Nina, which is what we have, you usually have warmer temperatures than normal.

"The weather's settled, we get big highs that settle over the country and no wind."

In the North Island the temperature on Christmas Day was likely to be in the low-20s, possibly reaching 26C in Auckland, Tauranga and Hamilton, said Weatherwatch.co.nz head weather analyst Philip Duncan.

In the main centres in the South Island it was expected to be 18-22C and it could be as high as 30C inland, he said.

As outside temperatures are hotting up, so too is the water - making Christmas at the beach an enticing prospect.

In Auckland and Northland, the sea temperature has risen to 18C, up from 16C at the start of summer. Around the lower North Island it is 16-17C and South Island waters are 10-12C.

That's not tropical - Fiji can expect 26C sea temperatures and Darwin 31C - but it's pretty balmy for a Kiwi Christmas.

The mild sea temperatures in the north could bring some unwelcome visitors to our shores, Duncan warned.

"The warm waters around Auckland and Northland tend to bring in more sharks, such as hammerheads.

"Great whites like the colder water and are more likely to be around the Chatham Islands and Dunedin."

Surf Life Saving New Zealand chief executive Grant Florence said with a longer, hotter summer on the cards, the organisation would increase its services to cope with swimmers flocking to beaches.

"If it's really fine weather at night we will probably stay on the beach rather than stop at 4.30pm."

While the expected warm weather makes for great summer holidays, it's not such good news for farmers.

In Northland, Waikato and Taranaki drought conditions are already setting in and a tough season may lie ahead.