Heavy downpours, thunderstorms, chilly temperatures and the chance of small tornadoes are possible today for parts of the country, forecasters warn.

It’s a wet start to Wednesday for some areas, with rain already bucketing down in Auckland as the nasty weather makes its way across the country.

The weather is slowing some commuters as they make their way to work, with surface flooding reported on the Auckland’s Northwestern motorway.

Traffic has also been backing up on the Southwestern motorway after a truck was forced to stop in a northbound lane just before the Waterview tunnel.

Police advised motorists to expect delays or take an alternate route. By 7.40am the blocked lane had been cleared.

A wet Wednesday is on the cards for much of the country with thunderstorms possible in the north!

This will help to alleviate lingering soil moisture deficits, although more rain will be needed

The lower South Island will have dry conditions pic.twitter.com/Mc0ecrPjg4

— NIWA Weather (@NiwaWeather) May 14, 2024

An area of low pressure is forecast to lie west of central New Zealand this morning, bringing with it an associated band of rain embedded with thunderstorms that will spread south over the North Island.

While overnight cloud meant warmer temperatures for northern parts of the North Island, compared with last week, the day has started with a moderate risk of thunderstorms for Northland and Auckland.

MetService predicts these thunderstorms will produce localised heavy rain in the range of 10 to 25mm/h. There is a low risk one or two severe thunderstorms about Northland will bring downpours of up to 40mm/h.

“The thunderstorms may also bring wind gusts of 80-90km/h, and there is a low risk of one or two small tornadoes about coastal areas,” MetService says.

The risk of thunderstorms spreads further south to affect the Coromandel Peninsula, northern Waikato and coastal Waitomo later in the morning and North Taranaki and western Bay of Plenty towards midday.

It's a return to umbrellas for the northern and central parts of the country on Wednesday as an area of low pressure brings wet weather, which could be heavy at times

The upper North Island may even be in for a thunderstorm in the morning with more intense bursts of rain pic.twitter.com/dueEWlCiwT

— MetService (@MetService) May 14, 2024

MetService meteorologist Mmathapelo Makgabutlane says the-low pressure system will bring “quite a bit of rain” with it, particularly for the eastern Bay of Plenty and top of the South Island.

“Most of the North Island will be seeing some rain and as it continues to drift across the rest of the country, [there will be] a lot of cloud and rain for the top of the South Island as well.”

Heavy rain watches came into effect for Tasman, about and west of Motueka, for 13 hours from 4am today and for eastern Bay of Plenty from 9am. Amounts of rainfall may approach warning criteria.

Heavy Rain Watch

It's looking like a wet Wednesday across much of the North Island and top of the South.

Severe Weather Watches for
The eastern Bay of Plenty
Tasman, west of Motueka pic.twitter.com/FtjvnN7sFZ

— MetService (@MetService) May 13, 2024

Meanwhile, temperatures in the top of the North Island will be slightly higher than those seen over the past week, with a high of 20C predicted for today in Northland and Auckland.

The rest of the North Island will see top temperatures in the mid-to-high teens and the lowest are set to be in the high single digits.

Overnight chilly temperatures were expected in the South Island, with the thermometer likely to get as low as 2C.

Mmathapelo says the bottom half of the South Island would see “beautiful, clear conditions” throughout the day.