Blocks of snow--not ice--are used in building igloos. The dome-shaped huts provide shelter by trapping warm air in their interiors.

Is it possible to build an igloo in sunny Southern California?

Of course, says Rick Maschek, a Fontana science teacher who has already built about 50 igloos across the country, including 30 in California.

The trick, he says, is to learn how to shape it like a dome.

Today, at 7 p.m., Maschek will teach a class on igloo building at the Recreational Equipment store at 602 Arrow Highway in San Dimas. The class is free.

Why would anyone in Los Angeles County need such a skill?

Although many people think the city is “hot and dry year-round,” Maschek says blizzards and snow lurk just 30 miles away in the mountains.

“If you know how to build an igloo, you may save yourself if you’re ever caught in a

snowstorm,” he points out.

This is especially useful for backpackers and cross-country skiers who lug heavy tents, said the 39-year-old Hesperia resident, who recommends carrying a 12-ounce snow saw instead.

The saw works much like a carpenter’s tool. It is about two feet long with thick blades and inch-long teeth designed to cut out blocks of snow. If the snow has good consistency, said Maschek, the saw will cut perfect squares or rectangles that resemble building blocks.

Maschek, who is also a search-and-rescue volunteer with the Barstow Sheriff’s Department, said many people think igloos are built with ice. But, he said, they are really made with snow, though some Eskimos use ice for windows.

The ninth-grade teacher said it takes from

45 minutes to an hour to build an igloo. The sleeping area is built higher than the opening to trap hot air, which rises.

An igloo is also warmer than a tent, inside which the temperature can average only 10 degrees higher than outdoors because of its thin nylon insulation, he said.

An igloo, by contrast, may be about 20 degrees warmer inside because of its one-foot thick snow walls, which insulate by trapping body heat or heat from a candle or stove.

“It may get so warm inside that the igloo may start to melt,” Maschek said. “You’ll have to punch holes in it to let the warm air out.”

An igloo is also soundproof. “You may be inside with a raging blizzard outside, and it’s perfectly quiet inside,” he said.