A heavy rain watch is in place for Bay of Plenty.

MetService said the yellow watch would commence midday Saturday for areas west of Rangitaiki River and remain until midnight.

A watch for areas east of Rangitaiki River was in place between 3pm Saturday and 3am Sunday.

The region could expect periods of heavy rain with a high chance of an upgrade to an orange warning.

“Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible,” MetService said.

The watch is also in place for Coromandel, from noon to midnight.

MetService said the unsettled weather was caused by a complex trough affecting the central and upper North Island while a cold front moved over the lower South Island.

From Sunday, a strong west to southwest flow spreads across New Zealand with mainly fine weather and a chance of a shower for Bay of Plenty.