The Met Office forecasts that snow showers will continue during the day on Tuesday and into the evening across most of Scotland.
ScotRail reported delays due to staff struggling to get to work, while Transport Scotland urged care, following a number of accidents early on Tuesday.
The amber warning is in place until 9pm.
Transport Secretary Michael Matheson said: “We’re being warned that parts of Scotland are expected to face another period of challenging weather, with the Met Office issuing an amber snow warning for Tuesday.
“The current Covid-19 restrictions mean you should only be leaving your home for an essential purpose, so please consider if your journey is absolutely necessary before setting off.
“The forecast conditions will likely cause difficult driving conditions and disruption to the wider transport network.
“If you do have to make an essential journey, then the advice remains the same as it has throughout this winter – plan your route in advance, drive to the conditions and follow Police Scotland travel advice.
“There may be disruption on other modes of transport, so you should check with your operators before setting off.”
Power cuts and disruption to telephone networks could also occur, Transport Scotland warned.
Areas such as Edinburgh and Glasgow have already faced a loss of electricity supplies amid the wintry weather.
Roads over higher routes are particularly expected to be affected by the snow and some rural communities might be cut off.
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