Bay of Plenty weather: MetService issues 42-hour heavy rain watch

A 42-hour heavy rain watch has been issued for the Bay of Plenty.

MetService updated its warnings this morning as a subtropical system north of New Zealand is set to bring wet, windy weather later this week.

The yellow watch is in place for areas west of Whakatāne from 9am Thursday until 3am Saturday.

There was a high chance of the watch being upgraded, with MetService warning that streams and rivers could rise rapidly, causing surface flooding, slips and difficult driving conditions.

Northland has been upgraded to an orange heavy rain warning, with 38 hours of rain forecast from Wednesday night.

The low-pressure system, which was near Vanuatu yesterday afternoon, is heading south over warm seas, where it could briefly develop into a tropical cyclone, before weakening.

The subtropical low is forecast to move west of the North Island tomorrow, bringing rain and strengthening northeasterly winds, particularly to northern regions.

By Thursday, the system is expected to intensify further while remaining west of the country, pushing bands of rain onto both islands and strengthening winds.