A weather expert says that while chilly nights are here to stay, the warm weather during the day is not set to go just yet.
NIWA principal scientist Chris Brandolino told Breakfast that, as the country heads towards autumnal equinox at 4pm tomorrow afternoon, New Zealand is transitioning to a period where the nights are longer than the days.
He added this means there is more opportunity for cooler air to bring down temperatures.
"The sun heats the earth. Without the sun, we don't heat the earth," Brandolino explained.
"We've had high pressure moving in and that high pressure creates clear skies, light wind, low humidity.
"That really is an ideal setup for all the heat that we accumulate during the day to escape into outer space.
"We call that, if you want to be nerdy, radiational cooling."
Brandolino said autumnal equinox is an "astronomical definition" where the sun crosses "an imaginary line", marking the start of a season. He said every year, the transition from summer to autumn is different and can sometimes be a "bumpy ride".
While the transition last year was defined as being wet, Brandolino said the theme is drier and chillier this year.
"I'm not saying it won't rain at all, of course it will, but it is just going to be less than what is typical of mid-March into mid-April.
"For example, we are going to get a bit of rain late this week into early this weekend, and perhaps some rain next week before the [long weekend] begins, but when you look at what is typical for this time of year, the expectation is much less of the country is going to find rainfall that is sub-par for this time of year."
Brandolino added this can provide challenging conditions, such as the top of the South Island where a medium-scale adverse event had been declared due to the lack of rainfall.
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