Residents across the Bay of Plenty are being warned to prepare for some heavy rain tonight.

The MetService has issued a severe weather warning for heavy rain developing across the region.

Heavy rain, seen here to the west, is being forecast for this afternoon through until tomorrow. Photo: MetService.

Fronts over the South Island have started to move north this morning, but are expected to become slow-moving over the Eastern Bay of Plenty this evening, says a statement from the weather organisation.

A MetService spokesperson says: 'Heavy rain that is affecting the northwest of the South Island, the Tararua Range and Mount Taranaki should ease this afternoon or early evening.

'In the South Island, a further 30 to 50mm of rain could accumulate on top of what has already fallen.

'For the Tararua Range and Mount Taranaki, another 60 to 80mm is possible before conditions ease.”

As the front stalls over the Eastern Bay, the ranges east of Whakatane can expect 90 to 120mm of rain from this evening until tomorrow afternoon.

People are advised that streams and rivers are likely to rise rapidly, with surface flooding and slips possible.