Corrigan said the warm weather was caused by north and northeast winds coming off hill country, which caused the air to warm and dry.
“That really heats things up.
“It’s called the Foehn effect and it’s responsible for the warmest temperature ever recorded in this country.
“That was around Rangiora, just north of Christchurch. Winds came over high country, in that case, the Southern Alps.”
Rangiora reached 42.4C on February 7, 1973.
Corrigan said high temperatures would remain for the next few days.
“It’s not really downhill from here. We are in for a warm, humid few days.
“Whanganui will be in the low-to-mid 20s, and it could reach 24C on Tuesday afternoon. That’s another potential record-breaker.”
There would be a bit of rain about, however.
“Tuesday should be largely a dry day but there is the chance of a shower,” Corrigan said.
“On Wednesday, we get rain turning up at the end of the day. That should persist through Thursday.
“Things do look a little bit better for the weekend.”
Overnight lows would remain mild, Corrigan said.
“That’s different to what we normally see at the start of May.
“Overnight lows are looking like 15C for most of the next week. It’s the northerly air stream coming out from the sub-tropics that brings warm air and cloud cover overnight.
“Maybe people can put their ‘going-into-winter’ blankets back in the cupboard. This week is a bit of an outlier.”
Corrigan said Whanganui would escape the heavier rain that was hitting Bay of Plenty and Coromandel.
“When the winds are like this, Whanganui tends to be sheltered from the worst of the heavy rain.
“In terms of fine weather, Tuesday and the first half of Wednesday are probably your best bet.”
