# Youyu County

Youyu County, also known by its Chinese name Youyuxian, is a county under the administration of the prefecture-level city of Shuozhou, in the northwest of Shanxi Province, China. It borders Inner Mongolia to the north and west.

## History

Shanwu, south of present-day Youyuxian, was the seat of Yanmen Commandery during the Qin and Western Han. The post moved to Yinguan southeast of present-day Shuozhou under the Eastern Han and further south to Daixian under the Kingdom of Wei.

## Geography

Elevations are generally higher in the south of the county, in which flows the Cangtou River (苍头河); Youyu reaches a north-south extent of 67.7 km (42.1 mi) and east-west width of 45.7 km (28.4 mi). The Great Wall demarcates the northwestern border with Inner Mongolia's Liangcheng and Horinger counties; within the province, Youyu borders Zuoyun County to the east, Shanyin County and Pinglu District to the south.

### Climate

Youyu has a monsoon-influenced, humid continental climate (Köppen Dwb), with cold and very dry winters, and warm, humid summers. The monthly 24-hour average temperature ranges from −14.3 °C (6.3 °F) in January to 19.9 °C (67.8 °F) in July, and the annual mean is 4.2 °C (39.6 °F). June thru September accounts for over three-fourths of the 407 millimetres (16.0 in) of annual precipitation. Due to the high elevation and dry climate, the diurnal temperature variation averages 16 °C (29 °F) annually.
Climate data for Youyu, elevation 1,346 m (4,416 ft), (1991–2020 normals, extremes 1971–2010) :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 8.7 (47.7) | 17.8 (64.0) | 24.1 (75.4) | 32.5 (90.5) | 33.4 (92.1) | 37.7 (99.9) | 37.0 (98.6) | 33.1 (91.6) | 33.1 (91.6) | 26.8 (80.2) | 19.5 (67.1) | 13.8 (56.8) | 37.7 (99.9) |
| Mean daily maximum °C (°F) | −4.2 (24.4) | 0.4 (32.7) | 7.3 (45.1) | 15.4 (59.7) | 21.6 (70.9) | 25.7 (78.3) | 27.1 (80.8) | 25.3 (77.5) | 20.5 (68.9) | 13.5 (56.3) | 4.7 (40.5) | −2.7 (27.1) | 12.9 (55.2) |
| Daily mean °C (°F) | −14 (7) | −9.2 (15.4) | −1.2 (29.8) | 7.0 (44.6) | 13.7 (56.7) | 18.3 (64.9) | 20.2 (68.4) | 18.1 (64.6) | 12.5 (54.5) | 5.0 (41.0) | −3.8 (25.2) | −11.5 (11.3) | 4.6 (40.3) |
| Mean daily minimum °C (°F) | −21.7 (−7.1) | −17.1 (1.2) | −9.1 (15.6) | −1.8 (28.8) | 4.6 (40.3) | 10.2 (50.4) | 13.6 (56.5) | 11.7 (53.1) | 5.5 (41.9) | −1.8 (28.8) | −10.3 (13.5) | −18.4 (−1.1) | −2.9 (26.8) |
| Record low °C (°F) | −37.3 (−35.1) | −33.7 (−28.7) | −29.3 (−20.7) | −17.4 (0.7) | −12.6 (9.3) | −2.1 (28.2) | 3.0 (37.4) | 0.7 (33.3) | −8.0 (17.6) | −14.0 (6.8) | −32.2 (−26.0) | −35.5 (−31.9) | −37.3 (−35.1) |
| Average precipitation mm (inches) | 2.5 (0.10) | 4.2 (0.17) | 8.8 (0.35) | 21.5 (0.85) | 41.0 (1.61) | 58.2 (2.29) | 105.6 (4.16) | 94.5 (3.72) | 55.8 (2.20) | 25.9 (1.02) | 8.4 (0.33) | 2.1 (0.08) | 428.5 (16.88) |
| Average precipitation days (≥ 0.1 mm) | 2.7 | 3.4 | 4.7 | 4.8 | 6.7 | 10.7 | 12.4 | 12.0 | 9.3 | 5.9 | 3.7 | 3.0 | 79.3 |
| Average snowy days | 4.4 | 4.9 | 4.8 | 2.2 | 0.3 | 0 | 0 | 0 | 0 | 1.1 | 4.2 | 4.7 | 26.6 |
| Average relative humidity (%) | 61 | 56 | 48 | 43 | 44 | 55 | 68 | 72 | 69 | 64 | 62 | 61 | 59 |
| Mean monthly sunshine hours | 205.3 | 205.2 | 244.4 | 266.1 | 285.5 | 262.9 | 252.6 | 244.8 | 225.9 | 231.9 | 205.0 | 197.0 | 2,826.6 |
| Percent possible sunshine | 68 | 67 | 66 | 66 | 64 | 59 | 56 | 58 | 61 | 68 | 69 | 68 | 64 |
| Source 1: China Meteorological Administration ||||||||||||||
| Source 2: Weather China ||||||||||||||