Boxing Day is bringing a mixture of wet and hot weather to much of the country.
The whole North Island is expected to reach temperatures above 20 degrees, with Napier and Hastings the hottest at 29 degrees.
However, showers and isolated heavy falls are possible with thunder in holiday hotspots in the northern half of the North Island.
A severe thunderstorm watch has been issued for Northland, Bay of Plenty, Gisborne and Hawke's Bay.
There is a risk of severe thunderstorms bringing localised downpours with 25 to 40 mm per hour in these regions. Rainfall of this intensity can cause surface and flash flooding, especially in low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.
A heavy rain watch has been issued for Northland, Bay of Plenty east of Rotorua and Tairawhiti/Gisborne.
Meanwhile, cooler temperatures are forecast for Canterbury and coastal Otago in the South Island.
"Conditions are drying out so some rain for the east coast of the South Island will be welcome today, starting out about Southland and Otago this morning, reaching Canterbury this afternoon and then perhaps eventually southern Marlborough. On the change moving through North Otago then Canterbury there is a chance of thunder," WeatherWatch said.
"The West Coast has some wet weather too, clearing up this evening. Nelson has a mainly dry day."
MetService added that eastern and inland South Island may also get thunderstorms on Tuesday.
Severe Thunderstorm Watch
Area: Northland
Period: 6hrs from 11am - 5pm Tue, 26 Dec
Forecast: A moist northwesterly flow is expected to bring frequent showers to Northland today. Thunderstorms are likely and there is a risk of severe thunderstorms bringing localised downpours, 25 to 40 mm per hour late morning and during the afternoon.
Area: Bay of Plenty, Gisborne, Hawkes Bay
Period: 11hrs from 1pm - midnight Tue, 26 Dec
Forecast: A moist northwesterly flow is expected to bring frequent showers and possible thunderstorms to parts of the North Island today. For the eastern Bay of Plenty, Gisborne and Hawkes Bay north of Napier there is a moderate risk of severe thunderstorms bringing localised downpours with 25 to 40 mm per hour this afternoon and evening.
Heavy Rain Watch
Area: Northland.
Period: 7hrs from 9am - 4pm Tue, 26 Dec
Forecast: Periods of heavy rain with thunderstorms possible. Rainfall accumulations may approach warning amounts over the area and possibly exceed warning amounts in localised areas. Rainfall rates may reach 20 to 40 mm per hour in one or two places, regardless of whether thunderstorms occur or not.
Area: Bay of Plenty east of Rotorua and Tairawhiti/Gisborne
Period: 11hrs from 2pm Tue, 26 Dec - 1am Wed, 27 Dec
Forecast: Periods of heavy rain with thunderstorms possible. Rainfall accumulations may approach warning amounts over the area and possibly exceed warning amounts in localised areas. Rainfall rates may reach 25 to 40 mm per hour in one or two places, regardless of whether thunderstorms occur or not.
MetService's short forecast
Northland to Waitomo, including Bay of Plenty, The central high country, also Gisborne and Hawke's Bay
Periods of rain or showers, sometimes heavy. Possible thunderstorms and localised downpours, all easing in the evening.
Taranaki, Whanganui and Manawatu, also the Tararua District
Isolated morning showers then mainly fine, but a few afternoon showers about the ranges.
Horowhenua to Wellington, and the remainder of Wairarapa, also Marlborough and Nelson
Long fine spells. Isolated showers spreading north from afternoon.
Buller, Westland and Fiordland, Also Southland and Clutha
Showers becoming isolated this morning, clearing by evening.
Canterbury, and the remainder of Otago
Showers spreading north, some heavy and possibly thundery with small hail.
Chatham Islands
A few showers.
