Pack on the sunscreen, drink plenty of water and seek sufficient shade today with the weather set to play ball on Auckland, Northland and Bay of Plenty Anniversary Day.
Today is tipped to be fine, kicking off with morning cloud before breaking out into a great day and reaching a high temperature of 26C in Auckland, despite early morning drizzle.
And it'll be even hotter in the South Island, with Blenheim tipped to reach 35C again today, the Met Service says.
By 7am on Monday, the temperature was already at 27 in Banks Peninsula.
Overnight tonight, the mercury isn't set to drop drastically, slowing as it reaches the low 20s where it will sit throughout the week from dusk till dawn.
"Auckland is going to start to see some really hot overnight temperatures," MetService meteorologist Ravi Kandula said.
"There will be unseasonably warm temperatures during day-time this week ... in the following days it's going to start to nudge towards the 30-degree mark."
Elsewhere, scorching temperatures into the 30s hit parts of New Zealand yesterday as hot air crosses the Tasman that saw oven-hot records set in Australia.
Blenheim, sitting at the top of the South Island, baked under 35C - the station at nearby Woodbourne recording 35.3C, meanwhile, midway down the island Christchurch sizzled at 30C
In the North Island, much of the east coast clocked in with temperatures around the low 30s with Hastings warmer than neighbour Napier by one degree at 32C.
Today the hottest parts of the country were tipped to be out east, MetService meteorologist Amy Rossiter said.
Gisborne was forecast to hit 34C, with similar conditions in the Hawke's Bay. In the South Island the hot spots would again be in the east with Blenheim on 35C, Kaikoura 33C and Christchurch 31C.
Warm temperatures were expected over summer, but the length of the extremely warm period was unusual.
"Some parts of the South Island might only get six days over 30C in a year, and this week they could get five or six days in a row," Rossiter said.
The warm air mass was forecast to stick around until Thursday before a front moved up the country Friday bringing cooler temperatures.
The impressive hot weather was driven by welting conditions over the ditch in Australia.
"The hot weather Australia suffered has helped warm the Tasman Sea and the air above it, helping to transport warm air our way," meteorologist Tui McInnes said.
"Which, combined with settled conditions, paves the way for some hot weather ourselves, especially for those in eastern regions."
The weather can be defined as a heat wave because a number of places throughout the country meet the threshold of one, Mcinnes said.
As defined by the World Meteorological Organisation, five consecutive days with maximum temperatures 5-degrees above average is a heat wave.
There are a number of events and activities today for Aucklanders to enjoy and partake in throughout the region.
At the Viaduct Harbour, there is the annual Anniversary Day Regatta and there is also a Dragonboat Regatta near Waitemata Plaza.
Laneway is also running tomorrow at Silo Park on North Wharf, meanwhile, at 9pm Vector will be putting on a display on the Auckland Harbour Bridge lights.
MetService's forecast for Monday
Whangarei: Fine. Southwest winds. High 28C, Low 20C.
Auckland: Chance morning drizzle in the west, then fine. Southwesterlies. 26C, 20C.
Tauranga: Fine and hot. Light winds and sea breezes. 30C, 19C.
Hamilton: Cloudy with chance drizzle morning and night, but fine during the day. Westerlies. 28C, 18C.
Napier: Fine and hot. Light winds and sea breezes. 31C, 18C.
New Plymouth: Morning drizzle, then fine until drizzle returns at night. Westerlies. 24C, 16C.
Wellington: Overcast with morning drizzle, but afternoon fine spells. Northerlies. 25C, 17C.
Nelson: Sunny and hot. Southwesterlies. 30C, 19C.
Greymouth: Rain easing to a few showers. Westerlies dying out. 21C, 15C.
Christchurch: Few spots rain around midday, then fine spells. But Low cloud late evening. Light winds, late easterly. 32C, 17C.
Queenstown: Early morning rain then fine and warm. Gusty northwesterlies easing evening. 28C, 12C.
Dunedin: Occasional morning rain then fine spells. Northerlies change southerly afternoon. 24C, 15C.
Invercargill: Cloud and the odd shower, clearing in the morning to fine. Westerlies, strong at times. 22C, 10C.