It is looking like another scorcher on Wednesday, with many spots around the country set to crack 30C.

Meanwhile, some spots in the South Island could see a dramatic temperature change later in the week as a cool change sweeps up the country.

MetService meteorologist Nick Zachar said a ridge of high pressure was sticking around the north and middle of the country, driving warmer temperatures today and tomorrow.

Most of the upper North Island would see temperatures in the high 20s today, with Tauranga the pick of the main centres on 30C.

Advertisement

Auckland is in for a fine day with light winds and a high of 26C.

It's good news for those wanting to hit Auckland's city beaches too, with all classed as safe for swimming at 6am, aside from those with permanent warnings.

The hot weather would continue through most of the week peaking on Thursday with the Coromandel, parts of the Waikato, Waitomo, Taumarunui, Rotorua, Taupō, Gisborne, Hawke's Bay and Wairarapa expected to reach the early 30s.

Blenheim would reach 33C and Christchurch 32C on Thursday. Auckland would also hit its hottest temperature for the week at 28C.

Meanwhile, the lower South Island West Coast would see some patches of rain late in the week as a series of weak fronts made landfall.

WeatherWatch NZ said these fronts would be accompanied by a cool change, with some parts of the lower South Island dropping eight to 12C by tomorrow from today's highs.

On Friday it would reach Canterbury, potentially dropping temperatures 10C there.

From Friday to Sunday another ridge of high pressure was expected to bring settled weather to much of the country.

Most of the weather activity was happening north of New Zealand, with category 1 Tropical Cyclone Oma forming near Vanuatu and other cyclones threatening to form near Fiji.

At 4am (NZ time) the Vanuatu Meteorology and Geo-hazards Department said TC Oma was moving towards the capital Port Vila.

At 2:00am local time today, Tropical Cyclone OMA (CAT 1)was located at 14.7 degrees South 165.8 degrees East. This is...

Posted by Vanuatu Meteorology and Geo-hazards Department on Tuesday, 12 February 2019

It was bringing damaging gale force winds and very rough seas with heavy swells to the islands Torba and Sanma.

People, including those on sea going vessels, were strongly advised not to go out to sea until the system moved out of the area. There was a risk of heavy rainfall and flash flooding over low lying areas and areas close to river banks, including coastal flooding for many areas.

Zachar said this would likely intensify into a category 2 cyclone in the next 48 hours.

"It is moving quite slowly, about two to three knots, meaning Vanuatu could see some strong winds, and damage from heavy rain and flooding."

Zachar said three other low pressure systems to the north of New Zealand near Fiji were threatening to form into one or two tropical cyclones in the next 36 hours.

"We are seeing quite and active weather pattern. The seas are very warm, 29 to 30C, and the lights are providing prime conditions for these systems to develop."

There was a "moderate to high chance" of one or two tropical cyclones forming in the next 36 hours, he said.

At this stage none of their weather models showed any systems affecting New Zealand.

Today's weather

Whangārei

Fine with light winds. 28C high, 16C overnight.

Auckland

Fine with light winds and sea breezes. 26C high, 16C overnight.

Hamilton

Morning cloud, then fine and warm. Light winds, but afternoon westerlies. 29C high, 13C overnight.

Tauranga

Fine. Light winds and sea breezes. 30C high, 19C overnight.

New Plymouth Morning cloud, then fine. Westerly breezes. 24C high, 13C overnight.

Napier Fine. Light winds and sea breezes. 28C high, 16C overnight.

Whanganui Morning cloud, then fine. Northwest breeze. 26C high, 14C overnight.

Wellington Fine, apart from morning cloud. Northerlies. 24C high, 17C overnight.

Nelson Fine. Southwesterlies turning northerly in the afternoon, dying out evening. 26C high, 16C overnight.

Christchurch Fine, but low cloud morning and night. Northeast developing from late morning. 26C high, 14C overnight.

Dunedin Fine, but morning and evening cloud. Northeast strengthening in the morning, easing evening. 24C high, 16C overnight.