The climate of Tajikistan, like any mountainous country lying in the southern latitudes, is very diverse: subtropical in the low valleys, moderately warm in the middle tiers of the mountains and cold in their high parts. For almost nine months, the balance of solar radiation in Tajikistan has been positive. This means that the surface in spring, summer and autumn receives more heat from the sun than it gives it to the world space.
In winter, the climate of Tajikistan is formed under the influence of cold continental Siberian and relatively warm and humid oceanic air coming from the west. In winter and spring, polar fronts often appear at the interface between air masses, along which cyclones move. Their passage is accompanied by snowfalls or rains.
In summer, the climate is determined by significant solar radiation; warm, dry, tropical air, formed over the deserts of Western and Central Asia, insulates the plains of the republic.
High mountains, holding back the cold air coming from Siberia in winter. Therefore, there are higher winter temperatures. Characteristic features of the climate of Tajikistan are large daily and seasonal fluctuations in temperature and dry air. The difference between summer and winter average monthly temperatures, for example, reaches 28-30°.
Mountains serve as a barrier to cold winds and make significant changes in the distribution of heat. In particular, when ascending from the Fergana depression to the Gissar-Alay ridges, the average air temperature drops in summer and winter, and when descending to the Gissar depression, and from it to the Vakhsh valley, it increases. This phenomenon is associated with the flow of air masses over the ridges, during which they are compressed, and the heat released during this heats the surrounding air. In the Pamirs, average monthly temperatures decrease when moving from west to east, where, due to an even greater distance from the Atlantic Ocean, the continentality of the climate increases.
The climatic seasons of Tajikistan are very different from the seasons of the countries of temperate latitudes. In the very south-west of the republic there is almost no snow and winter in its usual sense. There, throughout the year, the average monthly temperature is above zero. At least 2/3 of the year in the southern regions is warm or hot weather with temperatures from 10 to 30 degrees. The rest of the time; from December to February, it is cool, the thermometer shows from 1 to 5-6 ° of heat. At the same time, in the mountains at an altitude of 3000-4000 m, two or three months with a temperature above 10-15 ° are barely recruited. Cool or cold weather, winds, drizzling rains or snowfalls prevail there. Spring and autumn in the valleys of Tajikistan are short. In the lower mountain regions, frequent rains are observed in early spring, sometimes there are snowfalls. Autumn is dry, warm and perhaps the most pleasant time of the year. Depending on the temperature and the amount of precipitation, cold-humid (from November to April) and warm-dry (from May to October) periods are distinguished. In summer (June, July and August), on the plains of the north and southwest, the temperature ranges from 20 to 30 °. In the afternoon, it rises to 35-40°, and the soil temperature reaches 60-70° C. Such hot weather is favorable for some heat-loving crops.
The climate of Tajikistan allows growing medium-staple and fine-staple varieties of cotton here. For fruit growing, the duration of the frost-free period is of great importance. In the north of the republic it lasts 195-216, maximum 282 days, and in the south - 210-242 days, maximum 291 days. Fruit yields are strongly affected by spring frosts, which are caused by the intrusion of cold air masses from Siberia and sometimes coincide with the flowering of fruit trees. One of the features of the climate is the uneven distribution of precipitation over the territory during the year. The largest number of them falls in the cold period, and in the warm they are either absent or negligible. Therefore, agriculture on the plains is possible only with artificial irrigation.
Most of the precipitation brought by western winds remains on the slopes of the mountains, mainly in the axial parts of the Gissar Range, the ranges of Peter I and the Academy of Sciences. In this zone of high humidity there are basins of the upper reaches of the Varzob, Kafirnigan Obikhingou and the Fedchenko glacier. In it, from 900 to 1200 mm of precipitation or more falls annually, to the north and south of this zone - only 400-500 mm. In the South Tajik Depression, the amount of precipitation decreases from the northeast to the southwest. There are very few of them in cotton regions - only 150-300 mm. There is almost no rain from June to October, and the air heats up so much that raindrops from clouds that have flown from the mountains evaporate before reaching the ground. There is very little precipitation in the Fergana depression - only 100 mm. The Eastern Pamir receives the least amount of moisture in Tajikistan, where there is almost no snow and real rains.
Dry air contributes to the formation of dust storms in summer and sometimes in winter. They also come from other places. In Ferghana, a dusty, hot wind, usually intruding from the Karakum, is called garmsil. An Afghan is blowing in the south. These winds are accompanied by dry mist, which sometimes penetrates high into the mountains. Hot winds, although unfavorable for crops, usually do not cause much harm.
In the republic, depending on the height of the terrain and the nature of the relief, several types of climate are formed. The climate with very hot summers and mild winters dominates the plains located at altitudes of 350-500 m. It is characterized by a long (more than 200 days) summer and a small amount of precipitation - 150-200 mm. The climate, with hot summers and cool winters, is typical of the foothills of Kuhistan, the low mountains of the southwest, and the higher valleys. Precipitation here is 350-700 mm. A temperate climate is typical for the mountain ranges of Central Tajikistan and the Western Pamirs at an altitude of 1500-3000 m. Here, cool summers, cold winters, there is a lot of precipitation in the autumn-winter-spring periods. A cold climate reigns in the mountains at an altitude of more than 3000 m. The summer there is very short, the winter is long and frosty. High-mountain-desert climate is common in the Eastern Pamirs. Precipitation here is only 60-100 mm, mainly in the warm season. Summers are dry and short, but winters are harsh, with little snow and long. In places, under peat bogs at a depth of 1.5 m, permafrost soil occurs.