A heavy rain watch is in place for Fiordland and Westland, while snow flurries have been forecast for the Milford Road.
Earlier, MetService had forecast up to 4cm of snow to accumulate, but later advised that only flurries were possible near the top of State Highway 94 into this afternoon.
Meanwhile, multiple heavy rain watches are in place across the country for the end of the week, with upgrades to warnings possible, MetService said.
The culprit was a front preceded by a moist northerly flow expected to move slowly east across New Zealand tonight and tomorrow.
"It takes time to run in from the west on Thursday," MetService meteorologist John Law said.
Fiordland, north of Doubtful Sound, and the ranges of the Westland district were forecast to be hit first, with period of heavy rain from 11am today until 3am on Friday.
Law told RNZ this morning there could be bursts of "fairly intensive" rain accompanying thunderstorms this evening and into tomrorow.
"Could be some really intense bursts through there, 20-30ml of rainfall not out of the question as [the thunderstorms] run through."
People should keep a close eye on the weather forecasts.
MetService was working closely with the National Emergency Management Agency to ensure the weather watches and warnings were easy to use. That included a note about whether a warning was likely to be upgraded, he said.
"[This front] takes its time to clear through on Friday, there is some drier weather coming back towards us on Saturday with the worst of the rainfall now looking to be staying off down towards the far southern side of the country.
"It's going to be a one to keep a close eye on but I think the worst of the weather hopefully through Friday and things looking a bit better as we head into the weekend."
- ODT and RNZ
