The number of confirmed cases of the disease rose by 3,646, or 14.6 percent, to 28,572, according to health ministry figures, with officials warning infections will rise further in the coming days.
With 1,785 being treated in intensive care units for the virus, there is mounting concern about overcrowding at hospitals.
Prime Minister Pedro Sanchez warned late on Saturday that Spain's outbreak, already among the harshest in the world, would continue to worsen.
“We must prepare ourselves emotionally and psychologically for very hard days ahead,” he told the nation in a televised address late on Saturday.
“We have yet to receive the impact of the strongest, most damaging wave, which will test our material and moral capacities to the limit, as well as our spirit as a society,” he added.
Spain has issued lockdown orders for its roughly 46 million residents who are only permitted to leave their homes for essential work, food shopping, medical reasons or to walk the dog.