"They have been up in the 30s already this month, so this is a normal summer's day for them these days."
But the weather was about to cool again, Gullery said.
"There's a front coming across central and northern New Zealand ... a lot of cloud."
The weather in the South Island would improve slightly after a wet day yesterday, with temperatures reaching the mid to high teens.
"We do have some rain easing in places like Canterbury and Marlborough, but still quite a lot of cloud in those areas.
"Down around Otago and Southland, we should see a bit of clearance in the cloud and more sunshine."
A front would sweep across the country on Saturday, bringing rain to the west, Gullery said.
Temperatures would be "fairly warm" in eastern areas, but milder further west.
"Then on Sunday we've got a south-west flow across New Zealand, so there will be showery conditions from Taranaki northwards and across the west and the south of the South Island."
The middle and lower North Island was likely to have a "few cloudy periods and some long fine spells".
"Certainly the pick of the weather for the weekend would have to be Hawke's Bay and Gisborne, especially during Sunday."
Thursday's forecast
• Whangarei: Morning rain, a few afternoon showers and northerlies, 22C
• Auckland: Rain, easing to showers. Northerly winds, 21C
• Hamilton: Rain, then a few showers. Northerlies, 21C
• Tauranga: Rain, turning to a few showers. Northerly, 20C
• Wellington: Rain, easing to a few showers. Southerly, 17C
• Christchurch: Morning rain to spotted showers in the afternoon. Dying southerly, 16C
• Dunedin: Early showers, followed by cloudy periods. North easterly, 15C
