Emergency workers deal with a rolled vehicle in the ditch on Highway 16, near Maidstone. (RCMP)

A third day of winter weather is making highway conditions treacherous in some parts of the province, RCMP say.

On Wednesday, RCMP said highways around Maidstone, including Highway 16 and 21, were especially bad.

"A snow storm has hit this area over the past three days wreaking havoc on our roads and highways," RCMP said in a news release, noting the roads are covered with snow and ice.

Officers from the Maidstone detachment were dealing with a number of crashes, including jack-knifed semis and vehicles in ditches.

As of Wednesday afternoon, RCMP said road conditions were slowly improving, but motorists were being advised to drive "with extreme caution".

"If you do not have to travel, please delay your trip until conditions improve," police added.

Highway 16, both eastbound and westbound, was snow-covered with considerable ice.

Highway 21 north of Maidstone was also noted for "extremely poor" winter driving conditions.