Severe Weather Outlook

Issued: 10:34am Saturday 2 Mar 2024

Valid Monday 04-Mar-2024

On Monday an intense front sweeps northeast over the South Island and onto the lower North Island. At the same time a slow moving front over the North Island intensifies.

There is a high confidence that warning amounts of rain will accumulate in the north of Fiordland, the Westland District and the headwaters of the Otago and Canterbury lakes and rivers. There is a moderate confidence that warning amounts of rain will accumulate for a broader area over the South Island including the remainder of Fiordland, the Grey District, Buller and the south of Nelson. There is a moderate confidence that warning amounts of rain will accumulate over much of the central North Island, the Tararua Range and the eastern ranges of the Bay of Plenty.

There is a high confidence that severe northwesterly gales will affect Fiordland, inland Southland, Central Otago, the Southern Lakes and the Canterbury high country. There is a moderate confidence that northwesterly gales will become severe over the the remainder of the South Island apart from coastal Westland, Buller and Nelson. There is a high confidence that severe northwesterly gales will affect Wellington, Wairarapa and Hawke's Bay south of Napier, but a moderate confidence in severe northwesterly gales from Waitomo to the eastern ranges of the Bay of Plenty and inland Gisborne through the central North Island high country to Kapiti. There is a low confidence in severe northwesterly gales over the remainder of the North Island. Note that the gales over the South Island are likely to ease Monday morning but persist through much of the day over the North Island.

Valid Tuesday 05-Mar-2024

There is a moderate confidence that severe northwesterly gales will affect Wellington, Wairarapa and Hawke's Bay south of Hastings. These gales are expected to ease Tuesday afternoon. There is a moderate confidence in severe southwesterly gales for Stewart Island, coastal Southland, Clutha and Dunedin.

Valid Wednesday 06-Mar-2024

A ridge of high pressure brings settled weather to much of the country on Wednesday.

Valid Thursday 07-Mar-2024

A weakening front is expected to affect Fiordland and there is a low confidence that warning amounts of rain will accumulate there.

Low confidence:

A 20% likelihood (or 1 chance in 5) of a warning being issued.

Moderate confidence:

A 40% likelihood (or 2 chances in 5) of a warning being issued.

High confidence:

a 60% likelihood (or 3 chances in 5) of a warning being issued.

New issues of this forecast are made available on this site at or before 16:30 NZST

Thunderstorm Outlook

Valid to Midnight Saturday, 02-Mar-2024

Issued: 8:54am Saturday 2 Mar 2024

A front in the Tasman Sea will move onto the South Island today, while a second front moves onto Fiordland late in the day. A northwesterly flow precedes the first front, bringing scattered rain and a mix of surface based and elevated thunderstorms to parts of central and southern New Zealand today. There is a moderate risk of a few elevated thunderstorms about Golden Bay, the northern Marlborough Sounds, northern Wellington, Horowhenua and Kapiti (including the adjacent sea area) this morning or early afternoon, and a low risk about Wairarapa and southern Manawatu this afternoon. If any thunderstorms do occur, they will bring brief heavy rain. About the west of the South Island, there is a moderate risk of thunderstorms about Westland and the Canterbury High County near the main divide late morning to early evening, and about Buller and western parts of Tasman (including Nelson Lakes) this evening and night. These thunderstorms will be embedded within broader areas of rain and will boost local rainfall areas to 10-25mm/h (or possibly a little higher). For the Kaikoura area. North Canterbury and inland Mid Canterbury, there is a low risk of a few thunderstorms, or lightning originating from orographic wave cloud, from mid afternoon to tonight. If any thunderstorms do occur, they may produce brief localised heavy rain. For South Canterbury, Otago and Southland, there is a moderate risk of a few thunderstorms this afternoon and evening about eastern areas between about Oamaru and Edendale, and a low risk elsewhere as indicated on the chart. Any thunderstorms that occur will bring brief heavy rain of 10-20mm/h and possibly small hail. For Fiordland, there is a low risk of a few thunderstorms embedded within broader areas of rain this evening or tonight. Finally, there is a low risk of a few elevated thunderstorms about western Tasman and Taranaki late evening or tonight. No other thunderstorms or significant convection expected over New Zealand today.



Valid to Noon Sunday, 03-Mar-2024

Issued: 8:34pm Saturday 2 Mar 2024

Chart reviewed at 8:30pm Saturday and only minor changes made. A front will move onto the lower and central North Island during Sunday morning, while a second front moves northwards over the South Island. These fronts bring rain or showers, along with a thunderstorm risk to many parts of the country. In the western North Island, there is a moderate risk of thunderstorms embedded within broader areas of rain about Taranaki and inland Whanganui before dawn. then about Taumarunui, Waitomo and western Waikato later in the morning. A low risk covers many other western North Island areas during the morning as indicated on the chart. These thunderstorms will boost rainfall rates to 10-25mm/h. In the east of the North Island, there is a moderate risk of a few elevated thunderstorms and/or lightning associated with orographic wave cloud about the broader Wairarapa, Tararua District and southern Hawke's Bay area through much of the morning, and a low risk about other parts of Hawke's Bay and Gisborne/Tairawhiti mid to late morning. If any thunderstorms do occur, they may produce brief localised heavy rain. Over the upper South Island, there is a low risk of a few thunderstorms about Tasman/Nelson and Marlborough just after midnight, and also a low or moderate risk of elevated thunderstorms and/or lightning associated with orographic wave cloud about southern Marlborough, Kaikoura and North Canterbury before dawn. If any thunderstorms do occur, they may produce brief localised heavy rain. On the South Island west coast, there is general low risk of thunderstorms associated with a front moving northwards through the area, but the risk is considered closer to moderate about northern Westland and southern Buller for a time around dawn. If any thunderstorms do occur, they will boost local rainfall rates to 10-25mm/h. Finally, there is a low risk of one or two thunderstorms about eastern Southland, Otago and inland South Canterbury before dawn. No other thunderstorms or significant convection expected over New Zealand on Sunday morning.



Valid to Midnight Sunday, 03-Mar-2024

Issued: 8:35pm Saturday 2 Mar 2024

Chart reviewed at 8:35pm Saturday and no changes made. A weakening front should lie over the northern North Island during the second half of Sunday. As indicated on the chart, there is a low risk of a few thunderstorms about southern Northland, Auckland, Coromandel Peninsula and northern Waikato in the afternoon and early evening, and about the remainder of Waikato, Bay of Plenty/Rotorua, Gisborne/Tairawhiti, Hawke's Bay and the Tararua District in the afternoon. If any thunderstorms do occur, they may produce brief localised heavy rain. There is also a low risk of thunderstorms embedded within broader areas of rain about Fiordland from evening. No other thunderstorms or significant convection expected over New Zealand during this period.



Severe Thunderstorm Criteria

In New Zealand, MetService classifies a thunderstorm as severe if one or more of the following criteria are met:

Heavy rain (from thunderstorms):

Rainfall of 25 millimetres per hour, or more.

Large hail:

Hailstones 20 millimetres in diameter, or larger.

Strong wind gusts (from thunderstorms):

Gusts of 110 kilometres per hour / 60 knots or stronger.

Damaging tornadoes:

Fujita F1 (wind speeds greater than 116 kilometres per hour / 63 knots) or stronger.