The watches are for heavy rain in Northland, Auckland, Coromandel, Waikato and the Bay of Plenty, and potentially severe gales in Waikato, Waitomo, Taumaranui and Taranaki.
And there's not much light on the horizon, with the rain expected to settle in for the rest of the week.
"It is going to be very wet to start with and a few showers lingering through the middle of the week. It eases back on Wednesday, Thursday, Friday but there might be some more wet weather in the wings on Saturday.
"General story for the North Island tomorrow, in addition to those places with watches, is most places are going to get some rain with heavy falls."
By Tuesday, the east coast of the South Island would also get rain, and gales were expected on the west of the North Island and upper South Island, she said.
Snow was expected down to as far as 600m in Otago on Wednesday.
Temperatures should remain relatively steady, Ms Blades said.
"The early morning temperatures are particularly mild.
"Because you've got that cloud cover and the air's quite warm it's keeping those temperatures up in the double digits for a lot of the North Island."
WeatherWatch said the country would see "generally mild" weather with plenty of rain over the next two weeks.
It was not necessarily good news for ski bunnies, with more rain and cloud forecast instead of frosts and snow, WeatherWatch said.
"The first week of spring looks fairly typical - but may be slightly warmer than average, with another low coming back in next weekend bringing wind and rain to a number of regions."
Monday's forecast
• Whangarei: Rain with heavy falls. High 17C
• Auckland: Rain developing, heavy falls. High 14C
• Hamilton: Cloudy, rain by noon. High 14C
• Wellington: Cloudy with light showers. High 11C
• Christchurch: Cloudy with morning and evening drizzle. High 9C
• Dunedin: Mostly cloudy, drizzle at times. High 8C
• Queenstown: Morning and evening cloud. High 12C
Tuesday's forecast
• Whangarei: Heavy rain, easing to showers. High 19C
• Auckland: Heavy rain, easing at midday to showers. High 17C
• Hamilton: Rain at times, possibly heavy. High 16C
• Wellington: Rain, strong southerlies dying. High 14C
• Christchurch: Periods of rain. High 10C
• Dunedin: Mostly cloudy, drizzle at times. High 9C
• Queenstown: Mostly cloudy, chance of rain. High 11C
- NZME