"What people would have felt overnight is about the same as daytime highs for the month of October. It's looking to be a trend for the rest of the week," Makgabutlane said.
The temperature only dropped below 15C at 5.30am on Wednesday morning.
Napier and Hastings are in for a week of "muggy conditions", Makgabutlane said, with the average temperature forecast between 5C to 7C above what's expected at this time of year.
Makgabutlane said temperatures will hover around the early 20Cs for the rest of the week.
Cloudy conditions and light rain on Thursday will give way to sunny spells on Friday, with the promise of more warm weather for the weekend.
"Saturday looks to be a beautiful sunny day and there will be decent sunny spells on Sunday too, with temperatures averaging about 24C," Makgabutlane said.