The fine weather which has graced much of the country is set to turn sour as a trough moves in over the next few days.

Severe weather watches have been issued for Northland, Westland and Fiordland, but the MetService said those warnings were just "for starters".

Meteorologist Daniel Corbett said the trough would move in from the northwest.

"This week's trough is reasonably complex, the rain band is expected to drift across the country from the northwest during Tuesday.

"Further outbreaks of rain are likely in the days that follow."

He said as a result, raincoats would come in handy over the next few days as the weather would be quite "changeable".

The trough was expected to move in at the top of the North Island and the bottom of the South Island tomorrow, and bring with it high winds as well.

Corbett said as it swept over the rest of the country, wind and rain would settle in elsewhere overnight on Tuesday.

He said the system would linger until about Thursday and then peter out for the weekend.

"As the low develops, by the time we get to Thursday there will be the strengthening south to south-westerlies, and burst of heavy rain which will fizzle towards the end of the week."

Corbett said the system was currently gathering momentum as "different pieces of the puzzle came together" over the next day.

"There are two different lows, with one sitting out in the Tasman, and they're just going to organise themselves first as they come in at either end of the country."

MetService was advising people stayed on top of weather warnings, and to carry a rain coat as even if it wasn't raining, "rain will never be far away".

- © Fairfax NZ News