Sweltering Kiwi summer could add thunder to the mix today

New Zealand's hot, humid summer is not letting up with today set to be particularly warm, especially in the south.

Alexandra is tipped to reach 34 degrees and Invercargill picked to hit 29, with pretty much everywhere else likely to bask in the mid to high twenties.

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MetService says it's all down to warm air from the tropics remaining over New Zealand, boosting both temperatures and humidity.

TVNZ weather presenter Dan Corbett with the latest update. Source: 1 NEWS

Yesterday's moderate risk of thunderstorms for parts of both islands is heightened today for the North Island, the forecaster says.

A severe thunderstorm watch was in place for Northland from yesterday afternoon until early this morning. 

There's a reasonable chance of isolated thunderstorms with downpours today just about anywhere in from the coast and north of Palmerston North, MetService says. 

A heavy rain watch is also in effect for much of the upper North Island through to this afternoon.

TVNZ weather presenter Dan Corbett with the latest update. Source: 1 NEWS

And if you're hoping for quick relief from the sticky conditions, you're probably out of luck.

MetService says the pattern of warm days and afternoon heat showers is set to continue through to at least next weekend. 

It says several new temperature records could be set by the end of the month, with many centres already well above the January average.

Breakfast weatherman Matty McLean has the latest weather update. Source: Breakfast