Spain is in a race against time to clear roads covered by heavy snow, and get Covid vaccines and food supplies to areas affected by Storm Filomena.
As much as 20 inches of snow fell on Madrid, one of the worst hit areas, between Friday night and Saturday.
At least four people died and thousands of travellers were left stranded.
The Spanish government said it had taken extra steps – including police-escorted convoys – to ensure its expected shipment of some 300,000 coronavirus vaccines can be distributed as planned to regional health authorities on Monday.
Soldiers were out on Sunday clearing some of the 700 major roads that were still impassable in the morning. Some 500 people across the Madrid region were forced to spend the night in temporary shelter, including sports centres, after they were trapped by the whiteout.