Summer has started to heat up, with several places reaching the 30s on Sunday, and many others sitting high in the 20s.

Kaikōura airport topped the day's highs, reaching 32 degrees Celsius at 3pm on Sunday, while Timaru reached 31C and Napier edged in at 30C.

Places that reached the upper 20s included: Kaikōura's other weather station spots as well as Ashburton and Hastings which all hit 29C; Kawerau which reached 28C; and Gisborne, Whanganui, Hanmer Springs, Christchurch and Alexandra, which all recorded a 27C high.

Meanwhile, Waka Kotahi has placed speed restrictions on some parts of State Highway 67 on the West Coast due to flooding on Sunday, and MetService issued orange warnings for Sunday afternoon and evening, till 4pm and 6pm for Westland and Buller.

And severe thunderstorms were detected in the Christchurch area on Sunday evening.

What to expect from the weather on the week before Christmas

On Monday, cloudy or partly cloudy weather was expected to dominate the North Island down to the Wairarapa and Manawatū, with showers in some places, while drizzle in Wellington and Horowhenua would be clearing. The South Island was expected to be fine.

High pressure was expected to begin building across the country next week, setting the scene for a nice run of weather before Christmas Day for many areas.

Tuesday, Wednesday and Thursday were forecast to be mostly fine for much of the country, with rain starting in the south of the South Island from Wednesday and the east of the North Island on Friday.

It was still early to say what Christmas Day might bring.

"From Tuesday next week we can expect some more settled weather for most parts of the country," MetService meteorologist Lewis Ferris said.

This story was originally published by RNZ