MetService has issued a severe thunderstorm warning for Napier and Hastings.
The thunderstorm, which caused flash flooding in Auckland this morning, is moving down the country and heading east.
It is likely to bring very heavy rain, which could cause more flash flooding.
A severe thunderstorm warning has been lifted for Gisborne and Hawkes Bay. It remains in force for Waikato, Bay of Plenty, Rotorua, Taupo, Manawatu and Tararua.
Civil Defence advises that those in affected areas take shelter, secure loose items and move cars away from trees. Drivers caught in the storm should slow down or stop altogether.