After large parts of Spain were hammered by heavy rain this week, setting off the deadliest natural disaster in the country’s recent history, more downpours were expected on Friday, with inclement weather spreading to more regions and complicating an already strained rescue effort.

Heavy rain fell overnight in the southern region of Andalusia, with the western province of Huelva the worst hit. Residents were out celebrating Halloween when sheets of rain began to fall, local news media reported. It continued to rain on Friday, raising the risk of flooding in the area, Spain’s Weather Service warned. The authorities urged people to stay home, and avoid celebrating All Saints Day on Friday, which is usually done by visiting a cemetery or church.

“This Friday the most complicated situation will be in the southwest of the peninsula,” Rubén del Campo, spokesman for the national meteorological agency, said. “The instability will continue on Saturday.”

While the southwest of the country was on high alert, along the east coast rescue workers were still searching through piles of cars flung by floodwater and homes ripped through by mud. Rain continued to fall on Friday, particularly in Castellón, north of the Valencia region; in Tarragona, in the southern Catalonia region; and on the Balearic Islands, off Spain’s east coast, according to the weather agency.

At least 158 people have died, all but three in the province of Valencia, the regional authorities said. Dozens more remain missing, among them prominent business executives, older parents in nursing homes and young children trapped with their mothers, according to rolling coverage in Spanish media.