A front lying over central New Zealand has begun moving slowly northwards, signalling possible heavy rainfall across the region.

The front should bring some heavy falls to many of the North Island's hills and ranges on Saturday.

Heavy rain is expected to pummel the Bay of Plenty and the Coromandel this weekend. Photo: File.

This front has seen the MetService issue a watch for heavy rain for the Bay of Plenty and the Coromandel.

This watch covers the possibility that rain may come close to warning criteria in the Coromandel Peninsula and hill country of eastern Waikato and Bay of Plenty.

'The heaviest rain is expected from Saturday morning until Saturday evening,” says a statement from the MetService.

'People are advised to keep up-to-date with the latest forecasts and check for updates to this watch in case further areas are added or upgraded to a warning.”