The flowers may be blooming but those driving across the central and lower South Island are not free of the icy grip of winter just yet.

Cold southerly blasts continue to rudely interrupt the warming spring weather, and MetService is predicting conditions may be “favourable for large amounts of snow at higher elevations” again later this week.

A cold front is forecast to reach the South Island tomorrow (Tuesday 15 September), with heavy rain expected for western areas already sodden after recent storms. A MetService Heavy Rain Watch is in place for Fiordland from 5pm tomorrow.

Warm temperatures across eastern parts of the island are set to plunge on Wednesday, MetService says, with higher roads in for snow on Wednesday and Thursday.

Private forecasts supplied to NZ Transport Agency Waka Kotahi (NZTA) suggest a risk of 10cm of snow in the Mackenzie Basin impacting State Highways 8 and 80 early Thursday (17 September), while further north more than 10cm may fall on higher parts of State Highway 73 such as Porters Pass and west of Arthur’s Pass village.

NZTA’s roading crews will be monitoring the state highways – especially around the alpine passes -- and will be ready to clear snow or put in place closures or restrictions where necessary to keep people safe.

On State Highway 94 near Milford Sound, the cold front and accompanying rain is predicted to elevate the avalanche risk. Part of SH94 is likely to close from tomorrow evening (Tuesday 15 September), with a reopening currently expected around midday on Wednesday (16 September) after checks are completed.   

With the potential for closures and delays, people are advised to carry warm clothes, water and food in case they get stuck, or need to stop and wait for the weather to pass. Ensuring sufficient battery range or petrol in the tank is also advised in case there are detours and diversions required.

In heavy rain, NZTA reminds people to think about adjusting their speeds and travelling distances, avoiding sudden braking, and staying visible (using headlights in daytime hours). People are also urged to avoid driving through floodwaters where the depth is unclear and there may be hidden obstructions.

Stay up to date on the highway conditions at NZTA’s Journey Planner site.