The top of the North Island should brace for a burst of heavy rain tomorrow with the arrival of a Tasman Sea low, WeatherWatch.co.nz says.

Downpours were expected for Northland, Auckland and Coromandel Peninsula - with the risk extending into the Bay of Plenty and parts of Waikato, head analyst Philip Duncan said.

"The good news for holidaymakers is that both the heavy rain and the overall wet weather won't linger."

However, the low was expected to slow down as it moves southwards and runs into high pressure, which could allow rain to linger longer further south, Mr Duncan said.

But for northern areas rain should clear as Sunday wears on.

There was the risk of an isolated thunderstorm on Sunday, he said.

On Monday rain should ease to showers with New Years Eve still tipped to be mainly dry.

For northern New Zealand dry but sometimes cloudy weather was expected from Tuesday until Friday, Mr Duncan said.

Campers and trampers should be aware of rapidly rising streams on Sunday with the downpours moving - they may be somewhat tropical in nature due to the humid northerly flow - however temperatures were not expected to be especially hot with highs in the low 20's.

- APNZ