Meanwhile, the rain is expected to also start from 4am in the far south and move up the island. Up to 200mm is expected to fall across the Westland District ranges in an 18-hour deluge, bringing a threat of flooding, slips and difficult driving conditions.
🟠🟡Warnings & Warnings🟡🟠
An active front, preceded by strong moist northerlies, moves across the South Island on Monday, followed by showery westerlies.
Watches and Warnings are now in force for heavy rain and severe gusts ⚠️.
For more details, head to… pic.twitter.com/cDOmAeW8fZ
— MetService NZ (@MetService) December 13, 2025
“We’ve obviously had a brilliant weekend with the big ridge of high pressure over the country, but rapidly, there is a low in the southern Tasman, which is driving a frontal feature toward the country tonight into tomorrow morning,” meteorologist Devlin Lynden said.
“The most significant risk of rain will be in the alpine headwaters, as well as the West Coast, and that will drive rising river levels, which may cause surface flooding for those west, low-lying areas. There certainly is risk there [of flooding].”
While the parts of the country in the firing line for the fiercest winds wasn’t exceptional for those regions “you wouldn’t want to be out and about, particularly in the ranges in weather like this”.
Lynden said gusts of up to 120km/h are “always going to be potentially destructive” for foliage trees and powerlines.
“There’s certainly the risk of strong gusts causing damage.”
A warning is in place for the Canterbury High Country for 18 hours from 9am on Monday, with severe gale northwesterlies of 120km/h expected in exposed places.
Metservice expects winds to ease from the south from Monday evening.
Lynden said the rain would reach the North Island by Tuesday.
“Come midday there will start to be some rain for western areas of the North Island, such as Taranaki and Manawatu. Then by the evening, we’re expecting more widespread showers for Auckland, right through central North Island areas.
“There may be some heavier falls but it is quite a short period, so it’s unlikely that there will be significant risk of large scale flooding or anything like that.
“We don’t have any watches or warnings out for the North Island at this point, but there’ll be something to watch for tomorrow.”