Heavy rain warning for top of country

The top of the country has been warned of heavy rain and thunderstorms lasting until tomorrow afternoon.

MetService has issued a severe weather watch for Northland and Auckland as an active trough was expected to bring periods of heavy rain and thunderstorms.

It said rain was likely to at a rate of 25mm per hour, which could result in flooding, especially in urban areas.

Driving conditions could also be very hazardous, Met Service said.

WeatherWatch.co.nz analyst Philip Duncan said there was also a low risk of flash flooding.

"Not all suburbs will have heavy rain, but the risk for surface flooding extends across most of [Auckland], especially with autumn leaves blocking drains.''

Mr Duncan said on top of the recent deluges, and with cracks still in the ground from the drought earlier this year, there was an increased risk of slips and flooding.

"People should avoid being near cliffs along the beaches as this heavy rain could see slips and rockfalls.''

Due to heavy rain limiting visibility tonight and surface water, commuters should prepare for a slow journey home tonight from work, Mr Duncan said.