Severe Weather Outlook

Valid from Monday 30-Jan-2023 to Wednesday 01-Feb-2023

Issued: 10:50am Saturday 28 Jan 2023

A slow moving low is expected to remain just west of the upper North Island until Tuesday when it moves eastward into the Tasman Sea. This low delivers a feed of rain and heavy showers through the upper North Island during Monday and Tuesday, which spreads slowly southward on Wednesday and Thursday.

There is high confidence that rainfall accumulations will reach warning criteria about Northland on Monday and Tuesday, with a moderate confidence for Auckland and Coromandel Peninsula.
In addition, there is low confidence of northeast winds reaching severe gale at times in Northland and Auckland on Monday and Tuesday.

During Tuesday and Wednesday, there is a moderate risk of rainfall reaching warning criteria about western parts of Bay of Plenty and the Tasman Region, which spreads over much of the central North Island on Wednesday with a low risk (Taranaki to Bay of Plenty including central plateau and Waikato).

During Wednesday and Thursday, rain is expected about western parts of the South Island is affected, with a moderate confidence of warning amounts of rain for for central and southern Westland and northern Fiordland.


Low confidence:

a 20% likelihood (or 1 chance in 5) that the event will actually happen.

Moderate confidence:

a 40% likelihood (or 2 chances in 5) that the event will actually happen.

High confidence:

a 60% likelihood (or 3 chances in 5) that the event will actually happen.

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

Thunderstorm Outlook

Valid to Midnight Saturday, 28-Jan-2023

Issued: 8:39am Saturday 28 Jan 2023

Humid and unstable conditions are expected to continue over the northern and central North Island today. For most of the day, there exists a moderate risk of thunderstorms about the Hauraki Gulf, eastern Waikato, the Coromandel Peninsula, Bay of Plenty, Taupo, inland Gisborne and northern Hawke's Bay. If thunderstorms occur, they are likely to be accompanied by localised heavy rain with intensities of 10 to 25 mm per hour. Over Bay of Plenty and eastern Taupo there is a moderate risk that some of these thunderstorms will be SEVERE this afternoon, evening and tonight, bringing localised downpours with intensities of 25 to 40 mm per hour. There is also a moderate risk of thunderstorms this afternoon and evening about eastern areas of Northland, Auckland and Waikato, as well as all of Waitomo, Taumarunui and northern Taranaki. These thunderstorms may bring localised heavy rain with intensities of 10 to 25 mm per hour. For coastal Waikato south of Raglan, Waitomo, Taumarunui and northern Taranaki (from about Mount Messenger northwards), there is a moderate risk that some of these thunderstorms will be SEVERE, while further north the risk of severe thunderstorms is low. Downpours with intensities of 25 to 40 mm per hour are possible with the severe thunderstorms. Outside of these areas, there is a low risk of thunderstorms for all northern and central North Island areas, as shown on the chart. No other areas of severe convection or thunderstorms are expected.



Valid to Noon Sunday, 29-Jan-2023

Issued: 10:28am Saturday 28 Jan 2023

Humid and unstable conditions remain over the North Island during Sunday. There is a low risk of thunderstorms for all the North Island, north of about Palmerston North. For the Coromandel Peninsula, Bay of Plenty, Taupo and parts of Waikato and Gisborne there is moderate risk of thunderstorms during the morning. These thunderstorms may bring localised heavy rain with intensities of 10 to 25 mm per hour and there is a low risk of them becoming severe with downpours of 25 to 40 mm per hour. No other areas of severe convection or thunderstorms are expected.



Valid to Midnight Sunday, 29-Jan-2023

Issued: 10:38am Saturday 28 Jan 2023

The humid conditions, combined with afternoon heating is expected to lead to showers and possible thunderstorms forming over much of the North Island. As shown on the chart, there is moderate risk of thunderstorms in most North Island areas during the afternoon and evening, with the risk continuing into the night about Auckland and southern Northland. These thunderstorms may bring localised heavy rain with intensities of 10 to 25 mm per hour and there is a low risk of severe thunderstorms with downpours of 25 to 40 mm per hour. Outside these areas, there is a low risk of thunderstorms for the remainder of Northland, much of Wellington, Nelson and the Marlborough Sounds. No other areas of severe convection or thunderstorms are expected.



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.