Weather: What sort of summer can Whanganui expect?

The catalyst for those warm nights was likely because of the warmer seas around Whanganui - with ocean temperatures between 2C and 2.5C higher than normal, Ben Noll said.

Last month's warm and muggy days can be expected to continue throughout the summer, according to forecasts from Niwa.

The National Institute of Water and Atmospheric Research has published its outlook for the country over the next three months to February.

Niwa meteorologist Ben Noll said Whanganui could expect November's warm weather to continue, including "warm, sticky nights".

The catalyst for those warm nights was likely warmer seas around Whanganui - ocean temperatures are between 2C and 2.5C higher than normal, Noll said.

"Definitely might be something noticed if you're going for a swim.

"That keeps temperatures on land warmer as well."

Temperatures were expected to be above the country's average and rain was likely to be at normal or below normal.

"That's good news for the average person looking to enjoy the summer holidays.

"But for those with an agricultural focus, that will be something they will want to keep an eye on."

There were areas in Whanganui of "drier than normal soils" Niwa was looking closely at, Noll said.

"As we go through the coming weeks - it does look like patterns will favour drier conditions overall across the region."

Niwa said unusually warm seas were expected all around New Zealand and throughout the summer.

With those warmer waters, summer temperatures are expected to be higher across the country, including warm nights and high humidity.