Auckland and Northland are facing gale force winds, with heavy rain already drenching some areas this morning.

A severe weather watch is in place. 

MORE: Torrential rain hits campers in Northland

Northland Civil Defence spokesperson Shona Morgan said surface flooding is likely, and holiday makers camping in low lying areas are urged to monitor river and stream levels.

She says people need to exercise some common sense on the roads over the next few days.

"If you're travelling with trailers or campervans you just need to be mindful."

"You may need to travel a bit slower, it's going to be quite gusty out there."

The forecast:

A low lying northwest of New Zealand is expected to spread a broad rain-band over the North Island today (Friday), then over the upper South Island on Saturday, before cool southerlies spread over the country on Sunday. This rain-band is preceded by strong to gale easterlies, which are likely to affect northern parts of the North Island. The heaviest falls are likely about Northland, Auckland and the Coromandel Peninsula, where a warning is in force.

Areas where a warning is in force:

Northland

Periods of heavy rain are expected to ease Saturday evening. In the 39 hours from 9am today (Friday) until midnight Saturday, expect 150 to 200mm of rain to accumulate in northern and eastern parts, on top of what has already fallen, with over 100mm possible in remaining areas. Peak intensities of 25 to 35mm per hour in localised downpours. Note, showers still likely from Saturday night into Sunday morning.

Auckland and Great Barrier Island

Periods of heavy rain are expected to ease Saturday night. In the 39 hours from 9am today (Friday) until midnight Saturday expect 130 to 180mm to accumulate, mainly north of the Bridge and about the Hunua Ranges, with lesser amounts elsewhere. Peak intensities of 25 to 35mm per hour in localised downpours. Note, showers still likely through Sunday morning.

Coromandel Peninsula

Periods of heavy rain are expected to ease Sunday morning. In the 42 hours from midday today (Friday) to 6am Sunday, expect 140 to 180mm of rain. Peak intensities of 25 to 35mm/h in localised downpours Friday evening and Saturday morning.

Areas where a "watch" for heavy rainfall, that may turn into a warning, is in force:

Bay of Plenty and Waikato: From this afternoon until Sunday afternoon.

Mount Taranaki: From Saturday morning until Sunday morning.

Kapiti Coast and the Tararua Range: From Saturday afternoon until late Sunday morning.

Nelson and the Marlborough Sounds: From late Saturday morning until late Sunday morning.

Easterly gales may become severe in Northland, Auckland, Great Barrier Island and the Waikato until Saturday.