A severe weather watch has been issued for the Bay of Plenty region today.

The MetService says rain spreading southwards across the country

"A complex trough over the Tasman Sea is forcing a strong, moist north to northeast flow over New Zealand the coming days.

"Warnings and Watches are in force for many areas from Northland to Westland.

"People are advised to stay up to date with the latest forecasts in case further areas are added, or Watches are upgraded."

Area: Bay of Plenty west of Kawerau and Coromandel Peninsula

Valid: 18 hours from 3am to 9pm Wednesday

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.