Yes, igloos keep warm, and this is one of the major reasons why it is being built. Igloos are known to be warm inside, though the surrounding is cold. The outside, which is the surrounding of the igloo house, can be so cold on the temperature of negative 45 degrees Celsius, and the inside can be warm on a temperature of between negative 7 degrees Celsius and 16 degrees Celsius. Igloos are kept warm by body temperature, and you can also have some lights inside.
The inside of igloo is safe to accommodate candles and lanterns without any harm, which can also reduce the temperature of the igloo. In addition, snows are known to insulate, and thus makes the inside hot. Also, with the shape that an igloo house has, it does not allow and accommodate the blowing cold breeze to penetrate into it. The dome shape with which it is built resists the wind.