Is this a tornado or an impostor? Strange weather formation appears in rural Waikato

Watching the video, you might think a tornado was the latest in a long list of weather extremities to attack New Zealand lately, but you'd be wrong.

Climbing around three storey's tall and winding around itself, a swirl of wind and dust stuck out like a sore thumb for motorists near Waharoa.

Radio Sport broadcaster Jim Kayes was travelling through the area north of Matamata around 2.30pm when he spotted what looked to be a tornado.

"It's hard to guess it was but it was the size of a decent small roundabout or big tree," Kayes said.

"It was right beside the State Highway [27] outside of Waharoa, my biggest concern was that it might have been moving and might come onto the road.

"But it didn't - it was basically stationary but obviously spinning furiously at the bottom."

The formation was a dust devil, not a tornado. Photo / Ruth Kayes

However, MetService meteorologist Angus Hines said while it looks like a tornado, the formation was, in fact, a dust devil.

Tornadoes and dust devils are both atmospheric conditions but they are very different, Hines said.

"A dust devil is caused as heating at the surface causes a warm, thermal updraft. In some cases, this updraft can form a weak circulation," he said.

"If this circulation then crosses a dry area with plenty of dust/sand, this will get caught up in the circulation and that is exactly what's happened here."

Hines said this dust devil was fairly tall and active but was not a tornado, despite looking very similar.

Tornadoes are very uncommon in New Zealand, on average about seven to 10 moderate to strong tornado events are reported each year.

They are typically 20-100m in diameter, track for just a couple of kilometres, and last only a few minutes.

Because they're extremely localised, the damage they cause is very confined to the tornado itself, although the violent winds can fling debris hundreds of metres.

New Zealand's tornadoes pack wind speeds of 115km/h to 180km/h - enough to tear roofs from buildings and tip vehicles.

Although climate change is expected to bring more severe storms to New Zealand over coming decades, it's harder to tell whether that will also mean a higher likelihood of tornadoes.

The dust devil was about the size of a three storey building. Photo / Ruth Kayes