Farmers in the Peruvian mountains have been hard hit by the cold spell
The cold spell has killed at least seven people in Peru, four in Bolivia and two in Paraguay.
In the latter, the authorities blamed the weather for the death of more than 5,000 cattle too.
Weather forecasters say a cold front from Antarctica entered the region almost a week ago.
On Friday, the Peruvian deputy education minister, Martin Vegas, said schools were closed in 43 provinces in 10 regions.
"They will remain closed next week as more snowfalls have been forecast," he said.
Thousands of llamas and alpacas have died in the cold weather.
Peruvian President Ollanta Humala visited some of the worst affected areas earlier this week.
He said blankets and alpaca covers were needed, as well as medicines and clothes.
In Bolivia, roads closed by the snow have disrupted supplies to mines in the province of Inquisivi, in La Paz.
Work in five mines in the region, which employ thousands of workers, had to be suspended since last weekend because of the snow.
Correspondents say they were running out of supplies.
One of the driest places on earth, the Atacama desert in northern Chile, also saw snow earlier this week.
Forecasters said the snowfall was the heaviest in the area, about 1,000km (600 miles) north of the capital Santiago, in three decades.
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