White Island eruption: Where will the ash hit?

A volcanic eruption on White Island has sent huge plumes of smoke and ash thousands of feet into the air.

Winds may be drifting towards the East Cape carrying ash with them, according to Weatherwatch.co.nz.

"Tonight winds look light and variable around the island," it said in a statement. "The size of this eruption should keep it fairly localised."

Satellite imagery shows the cloud of ash drifting towards the east. By dusk, it's expected these winds will reverse.

"Winds at the moment should see any ash/smoke remain at sea."

The Ministry of Civil Defence says ash fall could affect areas distant from the volcano.

Anyone living in or near affected areas is advised to stay indoors.

"When indoors, close all windows and doors to limit the entry of volcanic ash," said Civil Defence in a statement.

"If caught in volcanic ashfalls wear a dust mask or use a cloth handkerchief to cover your nose and mouth. Protect your eyes by wearing goggles. Wear eyeglasses, NOT contact lenses as fine ash will get under the lens."

It also warns the effects of a volcanic eruption can be felt many kilometres from the original site. 

The eruption occurred just after 2pm on Monday. St John confirmed at least 20 people were injured in the blast.

Prime Minister Jacinda Ardern said in a press conference around 100 people were on the island at the time of the explosion, and a number of those are still unaccounted for.