"There is going to be a period of rain developing tomorrow, some of those could have some brief periods of heavy rainfall and possible thunderstorms specifically about the eastern ranges," he said.
Heavy rainfall would ease towards the evening on Monday, with Tuesday looking partly cloudy with a few showers, Griffin said.
"There will be a lot more settled weather towards the end of the week," he said.
Similar weather was forecasted for Tauranga, with rain developing in the morning.
Griffin said there was a chance rainfall could become heavy with a chance of thunder but would ease by the evening.
"Things are looking better towards mid-week," he said.