A heavy rain warning remains in place for the Bay of Plenty this morning.

The region was slammed with a deluge of rain overnight, causing road closures due to slips and flooding.

The Western Bay of Plenty, Whakatāne and Kawerau were under a red heavy rain warning from 6pm. A red severe thunderstorm warning was in place for Opotiki and Whakatāne. An orange heavy rain watch was in place until 3am Wednesday for Bay of Plenty including Rotorua.

Bay of Plenty Civil Defence was warning people to avoid travel, to stay at home and to check on loved ones and neighbours.

Flooding on Welcome Bay Road last night. Supplied video.

That warning is now been downgraded to orange and it's expected the MetService will review it at around 10am today.

Image: MetService.

The MetService is forecasting showers to develop later this morning.

"Heavy falls and thunderstorms are possible until the afternoon.

"Westerlies, strong at times from the morning."

The MetService warns that heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.