Issued at 2:04pm 22/12/2024

Valid from 2:04pm 22/12/2024 to 1:00am 23/12/2024

A shallow area of low pressure lies over the South Island, while a weak northwesterly flow covers the North Island. For the South Island, daytime cloud buildups are expected to produce scattered showers and/or thunderstorms about many regions this afternoon and evening, especially in the east. There is a moderate risk of thunderstorms for Canterbury, mainly from the foothills eastwards, North Otago, inland Dunedin, inland Clutha and eastern parts of Central Otago, with a surrounding low risk as indicated on the chart. Any thunderstorms that occur will likely produce localised heavy rain of 10 to 25 mm/h and hail of 5 to 15 mm diameter, but there is also a moderate risk a few of the thunderstorms could be severe producing localised downpours of 25 to 40 mm/h. A SEVERE THUNDERSTORM WATCH has been issued. For the North Island, scattered showers are also expected to affect many regions today, especially this afternoon and evening due to cloud buildups. Late in the day, a trough is forecast to move onto some western regions from the Tasman Sea. There is a low risk of thunderstorms for inland Waikato, inland Bay of Plenty including Rotorua, Taupo, eastern Taihape, eastern Whanganui, inland Manawatu, Hawke's Bay and the Tararua District this afternoon and evening. There is also a low risk of thunderstorms for western areas from the Kaipara Harbour to Taranaki tonight, as indicated on the chart. Also, although not depicted on the chart, there is a low risk of one or two thunderstorms for the Chatham Islands this afternoon and evening. No other thunderstorms or significant convection expected over New Zealand today.

Issued at 7:40pm 22/12/2024

Valid from 1:00am 23/12/2024 to 1:00pm 23/12/2024

Updated at 7:30pm Sunday - Moderate risk added to North Island west coast A trough embedded in a light west to northwest flow, along with an upper cold pool, are forecast to move over the North Island during the morning. This brings a moderate risk of a few thunderstorms to western parts of Auckland, Waikato and Waitomo (mainly near the coast) before dawn, and a low risk of thunderstorms from southern Northland and Great Barrier Island to Taranaki, Taupo and Bay of Plenty through much of the morning, as drawn on the chart. Late morning, sea breezes are expected to develop, causing showers to form where winds converge. There is a low risk of thunderstorms for Gisborne/Tairawhiti, Hawke's Bay, Taihape, inland Whanganui, northern Manawatu and the Tararua District. Any thunderstorms that develop bring brief heavy rain and small hail. No thunderstorms or significant convection expected elsewhere in New Zealand during Monday morning.

Issued at 7:44pm 22/12/2024

Valid from 1:00pm 23/12/2024 to 1:00am 24/12/2024

Updated at 7:40pm Sunday - minor changes only. A light west to northwest flow covers the North Island, while a shallow area of low pressure lies over the South Island. Over the North Island, there is a moderate risk of thunderstorms for Gisborne/Tairawhiti and Hawke's Bay during the afternoon, with a surrounding low risk that extends into the evening, as drawn on the chart. Any thunderstorms that occur will likely produce localised heavy rain of 10 to 25 mm/h and hail of 5 to 15 mm diameter. There is also a low risk a few of the thunderstorms could be severe producing localised downpours of 25 to 40 mm/h. Over the South Island, there is a moderate risk of thunderstorms for eastern Marlborough, and inland parts of Canterbury and Otago during the afternoon and evening, with a surrounding low risk, as depicted on the chart. Any thunderstorms that occur will likely produce localised heavy rain of 10 to 25 mm/h and hail of 5 to 15 mm diameter. There is also a low risk a few of the thunderstorms could be severe producing localised downpours of 25 to 40 mm/h. No thunderstorms or significant convection expected elsewhere in New Zealand during this period.