The shortened competition (18 instead of 21 stages) will mostly take place in northern Spain and in the region of the Basque Country before the finish line in Madrid on 8 November.
The authorities have declared a state of emergency for at least 15 days, which can be extended to six months.
In addition to the curfew, a limit of social gatherings and gatherings of a maximum of six people applies.
The regional governments may also decide to introduce restrictions on entry and exit from the regions, but the national border will be kept open for the time being.
- As it looks now, Vueltan will continue.
I have not received any messages about anything else so it will continue, says competition leader Guillen and comments on the curfew.
- It is between 23.00 and 06.00 and it does not affect Vueltan, says Guillen according to Dutch NOS.
"It's a ghostly landscape"
Primoz Roglic got rid of the red leader jersey on Sunday after the stable Jumbo Visma had problems putting on the rain jackets.
Ineos Grenadier's Richard Carapaz is the new leader in the competition.
The Swedes who are in Spain tell about a different everyday life.
- It is empty, deserted, it is like a ghost landscape, says Maria Strid who lives in the Barcelona area to SVT.
During today's rest day, covid-19 tests were performed on skiers and leaders who are in the bubble isolated from the outside world.
The results will be published before Tuesday's stage.
The stages planned in France have been redone, a fate that also affected the Giro d'Italia, as French authorities have imposed stricter restrictions and do not allow entry.
Spain has confirmed over 500,000 cases and 37,210 people with the virus have died.