More than 300 car accidents were reported in the south-western state of Baden-Wuerttemberg, with more than 40 people injured, Associated Press reported.
In the western state of North Rhine-Westphalia there were 108 reported accidents, while at the German-French border near Freiburg, hundreds of trucks were stuck for hours when French authorities closed the highway because of heavy snow.
Gale-force winds and drifting snow are expected to bring traffic to a standstill in many parts of Germany, a situation exacerbated by shortages of grit.
Airports have called in extra staff and rail operators have warned of delays.
Berlin's Schoenefeld and Tegel airports, and Munich airport reported cancellations.
On Friday evening, Nuremberg airport was closed briefly after an Air Berlin flight with 133 people on board skidded off the runway and became stuck in snow. No-one was injured in the incident.
The snow is already more than 30cm (1 ft) deep on the isle of Ruegen, off Germany's Baltic coast, ZDF TV says.
German households have been advised to keep three or four days' worth of provisions, including alternative cooking fuel in case of power cuts. Among the essential items listed by the BBK is a battery-powered radio, for checking weather reports.
In cities like Duesseldorf, Red Cross workers were setting up heated tents for emergency accommodation as up to 10 homeless people have frozen to death in recent weeks because of the cold weather.
In the UK, which is suffering its worst winter for decades, Prime Minister Gordon Brown pledged that gas supplies would not run out, and that road salt will get to "where it is most needed".
Temperatures have dropped as low as -22C (-8F) in some parts.
Local authorities have agreed to cut their use of salt by 25% in an attempt to preserve dwindling supplies.
British Airways cancelled 54 flights from Heathrow on Saturday. Delays were expected at other airports and low-budget airline Easyjet said it was cancelling some flights.
In the Netherlands, icebreakers have been deployed to clear shipping routes such as the Twente canal, the harbours of Almelo and Enschede and the Ijsselmeer inland sea.
Northern Spain is expecting more heavy snowfalls while the country's south has been hit by severe floods.
France is also braced for more snow. Meteo France warned: "The amount of snow expected is significant, exceptional even."
Parts of France - notably the south-eastern region of Provence - are without power and suffering transport delays after up to 20cm of snow fell in recent days.
Dozens of flights were cancelled in Toulouse, Lyon, Brest and Paris.
In the south-east, near the Mediterranean, power lines snapped under the weight of snow, cutting power to at least 7,500 homes.
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