"It might only amount to 5mm, but if you're on the ground in those few minutes it might have felt like significantly more."
Thunderstorms have mostly avoided Auckland, though lightning was recorded near Pukekohe this evening.
There were also thunderstorms near Great Barrier, Coromandel, Bay of Plenty and Taranaki.
McInnes said the showers would persist until the early hours of the morning, before easing throughout tomorrow and becoming more isolated.
The weather was expected to clear up for a sunny Saturday, which has a forecast high of 17C.
The heaviest rain was predicted to hit Wellington, where a southerly was moving in. Cooler temperatures were expected to come with it - as low as 9C tomorrow.
Today's weather
Whangārei Few showers, but afternoon rain, briefly heavy with possible squally thunderstorms. Northerlies change southwest afternoon. 21C high, 13C overnight.
Auckland Rain from late morning, briefly heavy with possible squally thunderstorms. Northerlies change strong southwest afternoon. 21C high, 14C overnight.
Hamilton A few showers. Rain this afternoon, heavy and possibly thundery, then showers. Northerlies change southwest afternoon. 21C high, 12C overnight.
Tauranga The odd shower. Rain this afternoon, heavy with possible squally thunderstorms, as northerlies change gusty westerly. 22C high, 13C overnight.
New Plymouth Rain, heavy falls with possible squally thunderstorms. Northwest change strong southwest. 20C high, 11C overnight.
Napier High cloud increasing. Rain from late afternoon, chance heavy, clearing evening. Gusty northerlies turning westerly at night. 23C high, 11C overnight.
Whanganui A few showers. Rain from afternoon, possibly heavy. Northerlies change westerly evening. 19C high, 12C overnight.
Wellington A few showers. Rain from around midday, possibly heavy. Strong northerly, changing strong southerly afternoon. 18C high, 11C overnight.
Nelson Rain. Strong northerlies easing in the morning, changing southwest by evening. 19C high, 10C overnight.
Christchurch A few showers, then clearing evening but remaining cloudy. Strong southerlies gradually easing. 15C high, 9C overnight.
Dunedin Mostly cloudy. A few showers clearing during the morning but returning at night. Southwesterlies. 15C high, 9C overnight.