Urafirth and Ollaberry Primary Schools closed at 1pm today and Brae High School and Whalsay Junior High School at 2pm as snow returned following the weekend’s thaw.
The schools service said this was because of the condition of side roads and to enable pupils to get home before dark.
Although temperatures crept up during the day, they are due to drop again tonight and fresh snow showers are forecast.
Meanwhile flights to and from Shetland have suffered disruption today due to snowy conditions across the country.
Sumburgh Airport has remained open but Edinburgh Airport has been closed all day, meaning all flights in and out of the capital have been cancelled. The airport is provisionally expected to be operating tomorrow.
Glasgow Airport was closed earlier in the day but has now re-opened, although flight delays in both directions are being experienced.
Today’s early flight from Sumburgh to Kirkwall and Inverness was cancelled and there was a delay on this afternoon’s incoming flight on the route as the plane was stuck in Glasgow.
However flights to Aberdeen have been arriving and departing normally, with only slight delays. A spokeswoman for Loganair said today’s problems had been on the mainland, not at Sumburgh.
Scatsta has been open all day, but delays in fixed wing aircraft flights has created a backlog of passengers. Helicopter flights have also been affected with only five flights managing to get offshore today.