"A complex trough of low pressure over the Tasman Sea moved onto the country late Thursday, bringing rain in a strengthening, humid northeast flow," he said.
"During Thursday, 24hr rainfall totals ranged between 15mm and 30mm on the Westland Buller coasts but between 40 and 50mm in the ranges of the Tasman District as a front passed over the regions."
Elsewhere, the South Island will see mainly settled weather tomorrow but overall temperatures should be on the cooler side, WeatherWatch reports.
The upper South Island will see a few morning showers but will clear up for a mostly sunny, mainly fine day.
"A fairly cool day ahead for most of the country, temperatures just getting into the mid-teens for Auckland and Northland," WeatherWatch said.
"A mix of sun and cloud about the rest of Canterbury. Sunny for South Westland and Fiordland after any early cloud clears.
"Southland and Otago have a mostly cloudy day with showers at times, drying out from afternoon with sun breaking through for inland areas."
Monday's weather outlook
Whangārei: A few showers, turning to rain at night. Southeasterlies developing. High 16C, Overnight low 9C.
Auckland: Occasional showers gradually clearing in the evening. Winds tending southeasterly. 15C, 6C.
Tauranga: Becoming fine in the morning. Southerlies developing morning. 15C, 5C.
Hamilton: Remaining showers clearing in the morning, then becoming fine. Southerlies developing. 14C, 1C.
Napier: Rain clearing by afternoon, but remaining cloudy. Southerlies. 13C, 5C.
New Plymouth: Becoming fine with southeasterlies. 14C, 5C.
Wellington: Cloudy periods. Isolated showers morning and night. Southerlies. 11C, 8C.
Christchurch: Partly cloudy. Chance evening shower. Southwest breezes. 12C, 0C.
Queenstown: Some morning cloud and early frosts, then fine. Light winds. 10C, -1C.
Dunedin: Cloudy periods. Chance afternoon or evening shower. Southwesterlies. 11C, 6C.
Invercargill: Mostly cloudy, a few light showers clearing evening. Westerlies. 11C, 5C.