Senior ranger Darren Roso said people did not understand why gates were on roads in times of snow, and pushed ahead not realising the damage they were doing.

"Snow is for skiing and building a snowman on, not for driving over,'' Mr Roso said.

"This place does not get a lot of snow, and so is not geared up for activity. People are spontaneous and do things unplanned and that can end in tears. They are poorly dressed, they have no chains for their vehicles.''

ACT Roads staff were also out in the mountains closing roads. Authorities say when snow falls, common sense deserts motorists who try to access areas in two-wheel drive cars.

"We are here to stop the nutters,'' one of the roads staff said.

The snow has not deterred wildlife. Wrens and wallabies skip and bound across the soft surfaces looking for food and shelter.

Closing Bundells Road gate in Namadgi, Mr Roso discovered someone had stolen the chain. He made do with a towing chain and a replacement padlock.

In the northern section of the national park the road provides an access into the Cotter catchment.

Three to four centimetres of snow covered the Bulls Head picnic section.

Mr Roso said roads were closed reluctantly, because rangers liked to encourage people into the bush to enjoy the snow with their families.

In 25 years looking after conservation areas in the mountains Mr Roso has seen snow heavy enough for cross-country skiing on only four occasions, including the time he travelled 30 kilometres from Aggie Gap to Laura Gap in the Brindabella Mountains.

He said there was nothing better for skiers and snow walkers to come across crisp white countryside unspoiled by car tracks.

Near Corin recreation area Craig and Fiona Gilmore and their daughter Amy jumped out of their car to catch snow flurries.

The Isabella Plains family were in California last week, in short-sleeved shirts enjoying 24 degree weather, and rugged up in coats and scarves on Tuesday to enjoy the gentle snow and white sky.