|
Landlocked Mongolia has a continental climate characterized by scant precipitation and sharp seasonal fluctuations. Siberian winters are legendary for their length and low temperatures, and Mongolia's
long cold winters last from October to April. Summer comes in July and August, when most of the rainfall occurs.
Thanks to the very strong Siberian High guarding the westerly approaches to Mongolia and the Himalayas to the south, low pressure systems are infrequent over the country. The anticyclonic influence is characterized by strong surface inversions, which can produce ground temperatures 10 degrees colder than those a kilometer above. The air inside this high pressure cell subsides and flows outward, creating persistent westerly and southwesterly winds across Mongolia. Low pressure disturbances must force their way around the stubborn high, typically passing south of the Yakutsk area on their way to the Sea of Okhotsk. What cloud cover that does reach the area generally arrives with upper level fronts attached to lows passing well to the north. Warm and cold fronts attached to these lows stretch southward across Mongolia and bring much of the springtime cloud cover. These warm air disturbances are lifted off the ground, unable to dislodge the cold air massed at the surface. The warmer temperatures which accompany this cloudiness may raise the mercury to the -20° C mark in midwinter, a phenomenon known as a Tuva thaw in southern Siberia.
Mongolia is a land of temperature extremes. The Gobi desert in southern Mongolia can reach 40°C (104°F) in the summer and fall to a bone-chilling -40°C (-40°F) in winter. Hovsgol Province in northern Mongolia experiences temperatures that can fall to a deadly -50°C (-58°F). Remarkably, the Mongolian capital of Ulaanbaatar has an annual average temperature - day and night, summer and winter - of just -0.5°C (31°F).
The average annual temperature in Mongolia's capital, Ulaanbaatar, ranges from -16°C (-2°F) in February to a more comfortable 16°C (62°F) in July. During the short spring transition in Ulaanbaatar, the average temperature climbs from 8°C (48°F) in May to only 14°C (58°F) in June. Summer fades quickly, and by September the annual average temperature drops to 8°C (48°F).
Precipitation is sparse in Mongolia, averaging only 378 mm (14.9 in) for the entire year at Ulaanbaatar. Winter in the Mongolian capital is very dry, averaging only 33 mm (1.3 in) from October through March. January and February are virtually free of precipitation. April and May bring a slight increase in rainfall, and the capital receives its greatest average precipitation in July and August; 161 mm (6.3 in). With only 40 mm (1.6 in) of rainfall in September, Mongolia's capital quickly resumes its dry winter season.
| 
