Sleepless muggy nights to continue as Auckland's weather looks to improve after thunderstorms

Thunderstorms and heavy rain have passed over the North Island, but muggy nights leading to unbearable sleeps are not going anywhere for the next month.

In Auckland warm and humid conditions are expected throughout the week, MetService meteorologist Josh Griffins said.

Aside from the thunderstorms, tomorrow is going to be a 🌞scorcher🌞, with 33 picked for Masterton and 31 for Christchurch🔥🔥 ^TA pic.twitter.com/cDoo2N00Jk

— MetService (@MetService) January 23, 2018

Drivers on the North Shore were stranded in swamped vehicles, more than a dozen homes were flooded and kids kayaked in the street as a storm cell dumped 62.4mm of rain on the area between 8am and 9am yesterday - the wettest hour in at least eight years.

Two drivers needed rescuing from their vehicles after they became submerged in the waist-deep floodwater, a section of Caribbean Drive was closed and lanes on the Upper Harbour Highway were blocked by the quickly rising floodwaters.

The rain also caused sewage to overflow into Castor Bay and Milford. Swimmers were advised to avoid the water.

The wet weather was expected to ease in Auckland last night and cloudy and patchy drizzle is expected today, moving to morning cloud and fine weather tomorrow. Friday would be partly cloudy.

But there would be a moderate risk of thunderstorms in the northern Hawke's Bay ranges, the Gisborne ranges and the Eastern Bay of Plenty, MetService meteorologist Heath Gullery said.

There was low risk for thunderstorms for inland Northland through to Wednesday evening and down south the ranges of Marlborough and central and eastern Otago also had a low risk.​

On Monday night Auckland recorded its highest measure of humidity this summer, recording an dew point of an uncomfortable 22C.

Niwa said the dew point, which is a measure of humidity, is caused by the sub-tropical northerly air flow and warm seas. It's deemed uncomfortable when it goes higher than 18C.

MetService forecaster Tom Adams said the general weather pattern causing the uncomfortably sticky nights was set to linger through February at least.

"For the next month we are going to continue seeing these warm temperatures," Adams said.

I swear I could cut the air in Hamilton with a blunt butter knife... you need a change of clothes to walk down the street! No rain tho... 🌤 #humidity #sticky #sohot @lovethetron @PhilipDuncan @WeatherWatchNZ

— Camille Guzzwell (@camtheguzz) January 23, 2018

He said westerly winds circling the globe were trapped in a jetstream high in the atmosphere, meaning cooler polar air was unable to surge out and produce a good southerly.

As a result, southerlies, which were counted on to bring respite from the heat, had not been "straight and true".

It was not helped by sea-surface temperatures well above average. Air moving on to the eastern coasts of the country in southerly flows was not being cooled by the sea as much in previous years.

As a result, temperatures across the country had not fallen below 10C overnight for some time, said the MetService.

Auckland has been warmer than 15C since January 1 as the average overnight temperature hit 18.6C.

Wellington too is fighting balmy conditions and average overnight lows of 16.1C and Christchurch has kept above 15C for the past six days.

Today's forecast

Whangarei: Drizzle becoming fine. High 28C Low 18C
Auckland: Drizzle becoming fine. High 27C Low 19C
Hamilton: Fine. High 28C Low 16C
Tauranga: Cloudy. High 29C Low 19C
Napier: Fine. High 29C Low 18C
Wellington: Fine. High 26C Low 19C
Christchurch: Fine. E. High 31C Low 16C
Dunedin: Cloudy then rain. High 22C Low 16C