A section of SH1, south of Ashburton, which was under a metre of water, was reopened late last night when the river level dropped.
However, police warned drivers to continue to show caution as there was still some surface flooding as well as high winds.
The town of Omarama was "on the edge" of a Civil Defence emergency yesterday, with water ankle-deep in the main street and up to a metre deep in other places.
Constable Paul Mander, of Kurow, said the town "just got by" without declaring an emergency, though 31 people were evacuated from the camping ground at 5.30am, along with three residents living near the river.
Lindis Pass, SH8 from Omarama to Tarras, remained closed because of flooding.
Environment Canterbury flood controller Graham Sullivan said the high levels of the rivers were caused by heavy rainfall in the Southern Alps, combined with snow melt and an already wet catchment.
He urged the public and river users to take care near all South Canterbury rivers, especially those that were rising fast or flowing swiftly.
MetService has warned that more snow is expected on the Milford Rd and Lindis Pass.
Up to 15cm of snow could accumulate on parts of the Milford Rd between today and tomorrow morning.
Light showers on the Lindis Pass this afternoon could also see 1cm of snow accumulating above 800m.
Meanwhile, winds of up to 120km an hour could hit the eastern North Island tomorrow.
MetService forecaster Mark Pascoe said areas between Havelock North and Eketahuna could be hit by the winds, which could fell powerlines and trees.
Bad weather caused further troubles around the country yesterday.
In the North Island, Taranaki was hit by a mini tornado yesterday morning.
Opunake resident Liney Lark was woken by a loud rumbling and the sound of smashing glass at 6am as the twister tore past her house.
"It was quite calm and then it was hail and rain really, really thick, then there was rumbling and I could hear glass smashing," Mrs Lark told the the Taranaki Daily News.
"It felt like the house was going to lift up."
The twister picked up a trampoline and flung it 40m into a paddock, smashed windows and flattened about 20 trees on the property, she said.
Another nearby resident, Andrew Pentelow, had 15 trees knocked over by the twister and his hay barn was thrown 100m across a paddock.
The region was also affected by lightning strikes, which downed powerlines and damaged transformers, cutting power to 230 properties.
In Hawke's Bay high winds blew a tree down across SH2 at White Pines Bush, about 15km north of Napier.
There was a brief spell of heavy, thundery rain in the Marlborough Sounds, Tararua ranges and Mt Taranaki in the morning, although it eased as the weather front moved towards the central North Island.
Metservice said another front was forecast to bring heavy rain to the ranges of Westland and Buller in the South Island this morning, but was expected to pass quickly with the rain falling for six to nine hours at the most.
- NZPA
