It's snow joke ... Boston's mayor has slapped a $50 fine on US secretary of state John Kerry for leaving the pavement in front of his home buried in the white stuff.

Martin Walsh vowed to crack down on shovel-shy householders and businesses after a blizzard dumped two feet of snow on his city this week.

And he proved he was not kidding when former US senator and Democratic presidential candidate Mr Kerry joined the list of offenders after failing to clear the snow from the side of his Beacon Hill mansion.

In fairness, Mr Kerry could have claimed he was snowed under at the time - he was in Saudi Arabia attending the funeral of King Abdullah with US president Barack Obama.

But his spokesman Glen Johnson told the Boston Globe Mr Kerry would promptly pay the fine and his pavement was later swept clear.