However, ahead of the front, temperatures climbed to the high 20s, and in places like Christchurch temperatures even reached 30C.
Tomorrow, cricket fans attending the World Cup match between Pakistan and the United Arab Emirates in Napier could expect good weather, with a warm, dry afternoon and a high of 24C predicted.
However, it could be a wet day for racegoers at the Auckland Cup at Ellerslie.
Ms Blades said Northland, Auckland, Coromandel, Bay of Plenty and Gisborne could expect a few showers tomorrow because of the moist air flow.
"Visitors dressing up for the Auckland Cup [tomorrow] may need to pack an umbrella."
Niwa forecaster Chris Brandolino predicted warmer temperatures for the whole country this autumn.
"For this autumn we are given equal chances for near normal or above normal [temperatures].
"The least likely outcome is for a cool autumn," he said.
However, as autumn progressed, cold snaps and frosts could be expected from time to time in some areas, Mr Brandolino said.
Analysts warn this week may provide a few sleepless few nights.
WeatherWatch said overnight lows would be warm enough to be "uncomfortable for some", because of the northeasterly flow.
Brighter nights were also expected with the moon waxing.
Dr Andrew Veale, clinical director at the New Zealand Respiratory and Sleep Institute, agreed that heat and humidity at night disturbed sleep quality.
"People toss and turn, have a fragmented sleep, and feel tired the next day," he said.
He said excessive light from the moon could also disrupt sleep patterns.