Weather: Fog, rain across New Zealand as humid front sweeps the country

Showers are blanketing large swathes of the country on Monday as stormy conditions make their way to our shores after a foggy, humid start to the week.

Weather Watch says a few fronts and troughs are extending out from a broad area of low pressure in the Tasman Sea, bringing patches of rain to New Zealand.

In the North Island, there will be showers from Wellington to Taranaki, as well as Northland and the Bay of Plenty on Monday morning.

"Rain becoming more widespread about the upper North Island this afternoon with heavy falls possible, rain also starts to ease about Northland later. Dry in the east but this evening rain spreads from the west into Hawkes Bay and Gisborne," Weather Watch says.

MetService has issued a severe weather warning in Taranaki, where a further 60-90mm of rain is expected to accumulate on top of what has already fallen, with peak rates of 15-20mm per hour.

"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous," the forecaster says.

A heavy rain watch has also been issued in the ranges of Bay of Plenty east of Whakatane.

The South Island will get a dousing too, with showers on the West Coast, Southland, coastal Otago, Nelson and Marlborough, though these will mostly clear away in the afternoon.

A heavy rain watch on the West Coast has now expired after 120mm of rain was recorded over the ranges in the last 24 hours, and 50mm nearer the coast in Hokitika.

It follows a foggy morning for most of the country after rain combined with the humid conditions overnight. MetService warns this is likely to be a common feature in coastal parts of the South Island this week.

NIWA Weather shared weather camera images of Christchurch and Auckland, both of which were completely blanketed in fog earlier on Monday.