Temperatures this week are warmer than average by several degrees in many regions as the country passes the spring equinox on Wednesday, says WeatherWatch.
The warmer weather is caused mild airflows from the sub-tropics, or simply mild nor'westers, says an update from the weather site.
This year the equinox for New Zealand occurs at precisely 1:30am on Wednesday, September 23.
After this date the days continue to become longer than the nights right up until the end of December, just before Christmas.
However, summer is still over two months away and we're only kicking off into true spring now, so expect more ups and downs - and a potential cold southerly is currently forecast for this Sunday and Monday, says WeatherWatch.
“It may bring a burst of lower level snow and a big drop in temperatures. It also looks relatively short lived, for a day or so.
“Spring is all about winter slowly fading away and hints of summer slowly coming in.”
Max temperature departure from normal for Monday. Image: WeatherWatch.