Antarctic climate is characterized by low temperature, high wind velocities, and frequent blizzards. Rapidly changing weather is typical of coastal locations, where temperatures for the warmest month average around freezing. Winter minimums drop as low as - 40°F ( - 40°C). High altitude and continuous darkness in winter combine to make the interior of Antarctica the coldest place on earth. Summer temperatures are unlikely to be warmer than 0°F ( - 18°C); winter mean temperatures are - 70°F ( - 57°C) and lower. The lowest temperature ever recorded on earth was - 128.6°F ( - 89.2°C) at Vostok, a Russian station. (Satellite sensors have recorded an even lower but unofficial - 135.8 [ - 93.2] in central East Antarctica.) Precipitation is in the form of snow; the annual water equivalent in the interior is c.2 in. (5 cm) and c.10 in. (25 cm) in coastal areas. In the dry, dust-free air one can see for tens of miles in clear weather; distances are deceptive, and mirages are common. Scattering of light by blowing snow or low clouds causes whiteouts, in which the sky blends with the snow-covered surface, eliminating the horizon; no condition is more feared by aviators.