A deep low was spreading across the country, meaning changes in temperatures in several regions. After glorious conditions on Saturday and Sunday, showers arrived in many parts of the region on Sunday afternoon.
Hastings and Napier didn't quite reach the anticipated 20C highs predicted on Saturday, with Hastings recording 18C and Napier 1C cooler.
The good news is that the cold shouldn't last too long, with things expected to "brighten up" from Tuesday on, Bellam said.
Weatherwatch.co.nz said the coldest air would  move in overnight on Sunday with windy westerlies building ahead of the low front and gale to severe gale southerlies kicking in behind it, especially around Cook Strait regions and the eastern North Island on Monday.
The Kaweka and Ruahine Ranges could see snow on Sunday night.
"Snow of 1cm or less may mix in with rain showers... It's possible some pockets may get 1 to 5cm if the right conditions prevail."