MetService says these temperatures could be equalled or surpassed today.
“People will be kicking off their blankets no doubt,” MetService meteorologist Lewis Ferris said.
Ferris said several factors were at play.
“There are a couple of things that need to come together,” he said.
“Usually a north or northwesterly warm, dry wind accompanied by existing warm, humid air, sunshine and time of year.
“Lingering around the country is this very warm, humid air that’s being dragged down from the north.
“That increases that base level of warmth, when you have warm air coming in, and then you have the warm wind, and then a little bit of sunlight in the mix as well.”
There are higher-than-average sea surface temperatures north of New Zealand.
“The air approaching the country is already warm and humid but it’s also coming across sea surface temperatures that are above average.
“So that is going to help with getting those elevated daytime temperatures here because a lot of our warm temperatures are going to be wind-driven.”
The cloud cover overnight acted as an insulating blanket, further trapping the warm air mass, coupled with light winds, which minimised cooling.
These same conditions are expected to continue today and overnight into Friday.
Whanganui is expected to reach daytime highs of 24C on Friday, 22C on Saturday and 25C on Sunday.
Overnight lows are expected to be 14C on Friday, and 12C on Saturday and Sunday.
“But Saturday looks like our dry day, with a wet period on Friday, and then the second half of Sunday as well.”
A day of rainfall can be expected on Friday, with diminishing northwesterly winds from today.
Saturday will be the pick of the weekend with dry conditions, potential for some high clouds and light, cool onshore coastal breezes.
Sunday will begin sunny but become more overcast with a chance of rain in the afternoon as northwesterly winds pick up again.
Saturday will be the day to target for outdoor activities or enjoying cooler, clear conditions.
