A severe thunderstorm warning has been issued for the Western Bay of Plenty and Rotorua.

At 6.30pm, MetService weather radar detected severe thunderstorms near Rotorua, Rotoehu, Rotoiti and lake Tarawera.

"These severe thunderstorms are moving towards the northnorthwest, and are expected to lie near Rotorua, Rotoiti and Okere Falls at 7pm and near Otanewainuku at 7:30pm," says an update from the weather organisation.

"These thunderstorms are expected to be accompanied by torrential rain, hail and frequent lightning.

"Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.

"Hail can cause damage to crops, orchards and vines and may make driving conditions hazardous.

"Frequent lightning is dangerous to people and livestock, especially those exposed outdoors or on the water, and can cause power surges and damage to electrical equipment."

The National Emergency Management Agency advises that as storms approach you should:
- Take shelter, preferably indoors away from windows;
- Avoid sheltering under trees, if outside;
- Get back to land, if outdoors on the water;
- Move cars under cover or away from trees;
- Secure any loose objects around your property;
- Check that drains and gutters are clear;
- Be ready to slow down or stop, if driving.
During and after the storm, you should also:
- Beware of fallen trees and power lines;
- Avoid streams and drains as you may be swept away in flash flooding.