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Lanzhou, the capital of Gansu province, sits in a narrow valley along the Yellow River in northwestern China, hemmed in by mountains at around 1,500 metres above sea level, at approximately 36.06°N, 103.83°E. On the edge of the arid interior, it has a cold semi-arid continental climate (Köppen BSk) — with warm, wetter summers and cold, dry winters — abundant sunshine and low rainfall, and a valley setting prone to trapping haze.
Summer, from June to August, is warm and the wetter season, with July the warmest month — average highs around 30–31°C — tempered by the altitude and low humidity, so the heat is dry and the nights cool. Most of the year's modest rainfall arrives in these months, often as thunderstorms, and the valley greens briefly against the surrounding arid hills.
Winter, from December to February, is cold and very dry, with January the coldest month — average highs around 1°C and lows near -8°C. Rain and snow are scarce, skies are often clear, but the narrow valley readily traps cold, stagnant air, dust and winter smog during still high-pressure spells, a persistent cold-season problem. Days are chilly but frequently sunny.
Lanzhou is dry, receiving only around 300–330 mm of precipitation a year, strongly concentrated in the summer months from June to September, while winter and spring are very dry; the aridity reflects its position on the edge of the northwestern deserts. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.
Lanzhou's narrow valley along the Yellow River, ringed by arid mountains, is the key to its climate: it gives dry, sunny, continental weather with cold winters and warm summers, but also traps cold air, dust and pollution in winter, historically making air quality a serious cold-season concern. Spring dust storms blown from the nearby deserts are another recurring feature of this Silk Road city.
To follow any single measurement in Lanzhou more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.