"For a lot of areas like Northland right through and down to Taupo, you're basically looking at areas of cloud or fog morning and night, otherwise fine during the day."
In the lower North Island and South Island, cloud would be heavier, and some drizzle was expected in Fiordland.
Maximum temperatures in Auckland would be in the mid 20s this week, with lows to 13C or 14C overnight.
Central and lower North Island temperatures would reach the early 20s and in the South Island they would sit in the late teens, dropping to single digits in both areas.
Niwa's seasonal summary will not be released until later this week, but climate scientists' outlook for March through to May was for average temperatures with less-than-average rainfall.
Ms Walsh said that forecast had been accurate so far, and the week ahead looked to be the same.
Daylight saving will recommence on September 28.
5 ways to enjoy the last of daylight saving
• Revisit the best of your summer BBQ favourites.
• Go for an evening walk - soon it will be dark before you finish work.
• Icecream - hold off on the soup just yet.
• Head to the beach/river/lake. It would also be rude not to have a swim while you're there.
• Make the most of locally grown summertime produce (before you have to start paying for the imported versions).