Your weather: Calm before the storm, heavy rain set to hit North Island tonight

It is the calm before the storm for the North Island today with heavy rain from the northeast set to arrive by tonight.

Cloudy, temperate weather with the odd patch of rain was on the cards for much of the country today.

MetService meteorologist April Clark said heading into Wednesday severe weather would spread across the country as an active front moved across both Islands.

"A deep low pressure system that develops over the Tasman Sea on Tuesday will be the conductor of this week's weather.

"Though the low is forecast to remain west of New Zealand it will direct a number of active fronts towards our waters, with the first expected on Wednesday."

Visibile satellite imagery shows a low pressure system forming in the Tasman Sea.

Notice warm/moist air being siphoned southward on the eastern flank of the system and cold/dry air charging northward on the backside <-- temperature differences drive mid-latitude weather systems! pic.twitter.com/HJex3srnGi

— NIWA Weather (@NiwaWeather) August 27, 2018

Strong northeasterlies and heavy rain were set to accompany the Wednesday front, with the worst hit areas expected to be the upper North Island and northwest corner of the South Island.

The Bay of Plenty region in particular was signalled to receive significant rainfall on Wednesday and possibly into Thursday.

Severe weather warnings were likely to be issued on Tuesday morning in anticipation of the front.

"Many other regions see deteriorating weather on Wednesday, due to northeasterlies ahead of the front that will drag in warmer, moister rain-laden air from the north," Clark said.

"This means that few New Zealanders escape at least a brief dose of rain."

The increase in moisture would also bring cloudier skies to the country compared to the weekend just gone.

A generally settled start to the week will breakdown early Wednesday as a low in the Tasman sea directs an active front onto NZ. Those in the northwest of the South Island & upper North Island should keep updated with their forecasts as heavy rain & strong winds are likely. ^AC pic.twitter.com/byviZ1wEoX

— MetService (@MetService) August 26, 2018

The weather for the later part of the week remains unsettled with the low pressure in the Tasman expected to continue sending fronts our way.

The changeable weather expected this week means it was an important time to keep up to date with latest forecasts, Clark said.

The front should move away to the east on Friday while the low moves southwards and deepens to the east of the country.

Today's weather

Whangārei

Cloud increasing, with a few showers, mainly from midday. Rain at night. Northeasterlies. 18C, high, 13C overnight.

Auckland

​ A few showers developing late morning. Northeasterlies becoming strong in the evening. 17C high, 12C overnight.

Hamilton

Morning fog, then fine. High cloud at night. Northeasterlies. 17C high, 10C overnight.

​

Tauranga

Cloud gradually increasing, and a shower or two from afternoon. Northerly breezes. 16C high, 12C overnight.

New Plymouth Morning cloud then fine, but cloud increasing again evening. Brisk northeasterlies. 15C high, 11C overnight.

Whanganui A fine day. High cloud at night. Northerly breezes. 18C high, 8C overnight.

Wellington Partly cloudy, chance morning shower, then fine. Northerly breezes. 14C high, 8C overnight.

Wellington Partly cloudy, chance morning shower, then fine. Northerly breezes. 14C high, 8C overnight.

Nelson Fine, evening cloud. Northeasterly developing by afternoon. 14C high, 8C overnight.

Christchurch Fine at first, but clouding over with a midday southerly and showers developing. Winds turning northeast afternoon. 14C high, 7C overnight.

Dunedin Mostly cloudy with occasional light rain, mainly morning. Southerly turning northeast afternoon. 13C high, 8C overnight.