At least 28 people are reported to have died in Iran's heaviest snowfall in recent years.
Eight people froze to death as severe blizzards left 40,000 people stranded in their cars, authorities said.
Although most have now been rescued, another 20 people are reported to have died in car crashes caused by the weather, officials said.
Tehran has declared two days of national holiday, urging people to stay at home to avoid the bitter cold.
The temperature has been down as low as -24 degrees Celsius, and for the first time in living memory there has been snow in the country's southern deserts.
Gas shortage fears
There are now concerns the severe temperatures may lead to a major shortage of gas used to heat many homes, reports the BBC's Jon Leyne in Tehran.
Tehran's new international airport has re-opened but the situation remains chaotic.
It is taking around five hours to get passengers from their planes out to their cars, our correspondent says.