'Incredibly unusual' heat driving extreme weather across NZ

Unseasonable heat is continuing to drive extreme weather in both the North and South Islands. 

Intense thunderstorms were reported over the central North Island around 2pm on Monday, along with heavy downpours in the upper South Island. 

The downpours are expected to continue to intensify until late afternoon, with the heaviest activity south of Lake Taupō, as well as along the Hawke's Bay and Gisborne Ranges.

WeatherWatch warns those in the main risk zones should be aware these downpours may include severe thunderstorms, locally gusty winds, hail and flash flooding.

Roxburgh in Central Otago has already experienced major flooding across the weekend, leading to evacuations and motorists being told to avoid the area. 

Phillip Duncan of WeatherWatch told Newshub drivers should also exercise caution if heading through the Desert Road or anywhere around Wairarapa. 

Mr Duncan said the weather events were in part driven by unseasonably high heats which he calls "incredibly unusual for this time of year". 

"We're seeing midsummer temperatures in mid to late spring, with eight degrees above average in Central Otago, day in and day out."

Mr Duncan said he thinks the extreme weather is driven partly by climate change but does not "read into it as much as others might".