Network Rail said snow patrol locomotives had been running on the Highland Main Line, Aberdeen-Inverness and Far North Lines but said the weather and road conditions for its response teams were treacherous.
And ScotRail said it had teams carrying out checks across the network, monitoring the snowfall depth.
Mark Ilderton, ScotRail’s service delivery director, told BBC Scotland News: “They will make sure we’ve got the most up-to-date information in our control centres and keep everyone safe and moving.”
Network Rail wrote on X: “We’ll likely see conditions worsen on all routes out of Inverness, where we could experience disruption due to deepening and drifting snow, coupled with the low temperatures.
“We’re unlikely to see much change on Sunday and Monday, with drifting snow in the north of Scotland and continued freezing temperatures and sharp frosts everywhere else. On Monday, we expect to see more widespread snowfall, spreading from the northwest.
“We’ll continue to work hard to keep the railway running, with teams working around the clock despite the conditions out there.”
