Tropical Cyclone Fehi will bring temperatures down in Northland but not the humidity

Shaleh Tawhi (left) and Violet Ngaruhe cool off at the Whangarei Falls, their favourite place to swim, which they describe as "perfect" to beat the summer heat. Photo / John Stone

Stormy weather will lower day and night-time temperatures in Northland but the mugginess is here to stay for a while longer.

Northland has sweltered through 12 consecutive days when the mercury has reached 25C or above, with an official high of 29.1C on January 25.

But with the temperatures recorded at Whangarei Airport it is sometimes more than 4C higher inland, and on January 25 the MetService recorded 33.1C at its weather station in Whau Valley.

Overnight highs of up to 21C have compounded the high daily temperatures and seen humidity levels soar to 80 per cent plus. The heat and humidity have seen people flock to the region's beaches and swimming holes.

But MetService said a deep low pressure as a result of the fizzled-out Tropical Cyclone Fehi in the Pacific Ocean will lower daytime temperatures in Northland from about 27C to 24C tomorrow. Overnight lows will come down to 15C or 16C over the weekend.

MetService meteorologist Lisa Murray said winds would gradually pick up today to stronger northeasterlies increasing to gale force for a time in exposed places tomorrow.There would be rain late morning tomorrow turning to heavy downpours in the evening, she said.

"We can expect Northland to continue with the current weather on Wednesday and into Thursday. Even though it will rain on Thursday, the humidity will be the same and it may even feel a bit muggier," Ms Murray said.

Houses retained heat and it could be a lot warmer inside than outside which meant people would have trouble sleeping, she said.

According to MetService weather data, most centres around Northland hit daytime temperatures between 21C and 29C throughout January and between 14C and 21C at night. The humidity would likely decrease next week.

The heat is also affecting animals, with the Bay of Islands SPCA attending several reports of dogs left inside vehicles this summer.

Centre manager John Logie said because of the vast area his office covered, he worked with other agencies such as police to ensure animals did not suffer unnecessarily.

He said none of the dog rescue callouts resulted in prosecution because owners were tracked down by the time SPCA inspectors arrived or got to their animals in time.

"If possible, do not take your animals in cars because it doesn't take long for them to heat and die when temperatures climb to mid and high 20s."

The temperature inside a vehicle was also likely to be far higher than the outside temperature.

Alexandra in the South Island was the hottest place in the country at 5pm yesterday at 35.4C.