The main A968 road in Unst will be closed from 5pm tonight (Saturday), the SIC has said.
That decision is due to “deteriorating” conditions in the isle.
“Strong winds are causing significant drifting snow, making driving conditions extremely difficult, particularly around the highest point at Cauldback Hill,” the SIC said.
Council staff will stop snow clearing and gritting, except for any blue light emergencies.
The Bluemull Sound ferry will also be tying up at Gutcher Ferry terminal from 5pm today for the rest of the night.
The council said the decision would be reviewed on Sunday morning, but added strong wind forecasts were expected to continue.