Niwa is urging beachgoers to get out of the water as cloud-to-ground lightning strikes pepper the Waikato and Bay of Plenty.
Nearly 80 strikes have been recorded in eastern Waikato and Bay of Plenty, however the thunderstorm was making its way north up the Coromandel coast about 1.45pm today.
Initially there were only 10 strikes recorded between Waihi Beach and Tauranga before the storm spread east into Waikato.
Seventy-seven strikes were recorded around Te Aroha, Paeroa, Ngatea and Waihi.
However, by 2.15pm today, the MetService was reporting more than 800 lightning strikes over a two-hour period.
The storm moved north a slight distance before veering east out to Whangamata.
Niwa urged people to stay out of the water and off beaches when there is lightning nearby.