Officials said snowdrifts and avalanches blocked roads in hilly northern Montenegro, where about 3ft of snow fell overnight.
The snow also blanketed the capital Podgorica, closing down the city's airport.
Podgorica and several towns along the Adriatic coast were left without electricity for several hours.
In Serbia, the top emergency official apologised for failing to clear the roads over the weekend, when hundreds were stranded in buses and cars.
In Croatia, doctors issued warnings to the elderly and sick to stay indoors.
At least nine deaths across the region have been blamed on the snow and deep freeze, with temperatures as low as minus 15C.
Elsewhere in Serbia, where snow began to fall on Saturday, officials said road crews were still struggling to even clear the central squares of some cities.