Eastern Bay of Plenty and Taranaki are feeling the brunt of the weather this morning, with heavy rain and thunderstorms.
The rain began over Whakatāne and just west of the town about 9pm last night, and has continued through this morning with 104.6mm recorded.
The heaviest period was between 3-4am, when 44mm fell.
The wet weather is tracking slowly to the east this morning and should be gone late morning, Dyason said.
Taranaki, Waitomo and Taumarunui are in for a similar day to yesterday, with some decent rainfall and thunderstorms on the cards through to tomorrow evening.
The rest of the North Island is in for a relatively fine day, with warm weather and just occasional showers forecast.
Nelson and northern parts of Marlborough could also see some heavy downpours to late Wednesday, with isolated thunderstorms.
A cold front is moving up the South Island on Wednesday, while the low causing all of the wet weather moves east over central New Zealand.
Rain or showers are expected for many places on Wednesday, with a high risk of rainfall reaching warning levels - 100mm over 24 hours - in Taranaki, Buller and Nelson, including the Richmond Ranges and Marlborough Sounds.
A west to southwest flow covers the country from Thursday to Saturday, with some fronts moving northeast Friday and Saturday.
These could bring heavy rain to northern Fiordland, Westland and Buller.
Westerlies could reach gale level about central areas on Friday and Saturday.
Today's weather
• Whangārei
Partly cloudy with a few showers. Northerlies. 22C high, 15C overnight.
• Auckland
Partly cloudy with a few showers. Northerlies. 21C high, 15C overnight.
• Hamilton
Cloudy periods. A few showers, especially evening. Northerlies. 20C high, 13C overnight.
• Tauranga
Often cloudy with a few showers. Northerly breezes. 20C high, 15C overnight.
• New Plymouth
Rain at times, with thunderstorms and possible downpours. Fresh northerlies. 19C high, 15C overnight.
• Napier
Occasional morning drizzle, becoming fine around midday. Northerlies developing. 19C high, 13C overnight.
• Wellington
Mostly cloudy with a few showers. Northerlies developing. 17C high, 13C overnight.
• Nelson
Periods of rain, heavy at times, with possible thunderstorms from afternoon. Northeasterlies. 16C high, 13C overnight.
• Christchurch
Cloudy. Occasional rain. Northeasterlies easing afternoon. 14C high, 9C overnight.
• Dunedin
Fine. Northeasterlies. 15C high, 7C overnight.