Covering period of Thursday 23 – Monday 27 November – MetService is closely monitoring a significant weather shift set to unfold as a large frontal system sweeps northward across the country. This meteorological event is poised to bring notable changes in temperature, strong winds, and heavy rain over the next 24 hours and into the weekend.
Today (Thursday), the eastern South Island braces for thunderstorm activity, accompanied by punchy winds and potential hail. MetService meteorologist Mmathapelo Makgabutlane emphasizes, “Rapid changes in weather conditions are expected with this frontal passage.”
Thursday boasts warm temperatures in Blenheim (28°C) and Christchurch and Ashburton (27°C). However, a stark temperature drop is anticipated as the cold front progresses from the South Island to the North Island by Saturday. Maximum temperatures on Friday in the South Island only reach the low to mid-teens, with Ashburton and Christchurch at a nippy 12°C and 13°C.
For the North Island, Masterton drops from 25°C on Thursday to 14°C on Saturday, while Auckland and Northland will transition to cooler and fresher air, departing from the “tropical feel” of late. Brief snowfalls are also possible in elevated areas of the lower South Island late Thursday into Friday.
A significant feature of this weather system is the arrival of strong and blustery southerly winds, affecting the eastern South Island and lower North Island. A Strong Wind Watch has been issued for Wellington, Marlborough Sounds, and the Kaikōura Coast for Friday from 2 pm to 11 pm. Makgabutlane advises, “Precautions are recommended, securing loose items and exercising caution on the roads, especially in exposed areas where gusts may approach severe gale.” Strong winds persist over the North Island during the weekend, especially in Gisborne and the Bay of Plenty.
These winds may also generate large waves in the lower North Island on Friday, extending to the eastern North Island on Saturday, with heights reaching 3 to 4 metres. Extra care is urged for those planning activities near the water during this period.
Lastly, the frontal system also brings rainfall for most of the country. The wettest conditions are expected to impact the eastern North Island on the back of an already wet start to this past week. A Heavy Rain Watch is in place for Hawke’s Bay and Tairāwhiti/Gisborne from Friday 1 pm to Sunday 9 am. “This is long period of wet weather, and residents are advised to stay updated with the latest forecasts, as areas may be added or upgraded in the coming days,” Makgabutlane says.
The weather system is expected to move away on Sunday, bringing improved conditions to the South Island and most of the North Island. The reprieve will be brief, however, as the next low-pressure system approaches in the new week. Details of this will be added in the coming days on MetService’s new look Severe Weather Outlook. MetService is New Zealand’s only authorised provider of Severe Weather Watches and Warnings.
Understanding MetService Severe Weather Warning System
Severe Thunderstorm Warnings (Localised Red Warning) – take cover now:
This warning is a red warning for a localised area.
When extremely severe weather is occurring or will do within the hour.
Severe thunderstorms have the ability to have significant impacts for an area indicated in the warning.
In the event of a Severe Thunderstorm Red Warning: Act now!
Red Warnings are about taking immediate action:
When extremely severe weather is imminent or is occurring
Issued when an event is expected to be among the worst that we get – it will have significant impact and it is possible that a lot of people will be affected
In the event of a Red Warning: Act now!
Orange Warnings are about taking action:
When severe weather is imminent or is occurring
Typically issued 1 – 3 days in advance of potential severe weather
In the event of an Orange Warning: Take action.
Thunderstorm Watch means thunderstorms are possible, be alert and consider action
Show the area that thunderstorms are most likely to occur during the validity period.
Although thunderstorms are often localised, the whole area is on watch as it is difficult to know exactly where the severe thunderstorm will occur within the mapped area.
During a thunderstorm Watch: Stay alert and take action if necessary.
Watches are about being alert:
When severe weather is possible, but not sufficiently imminent or certain for a warning to be issued
Typically issued 1 – 3 days in advance of potential severe weather.
During a Watch: Stay alert
Outlooks are about looking ahead:
To provide advanced information on possible future Watches and/or Warnings
Issued routinely once or twice a day
Recommendation: Plan
