Huailai (simplified Chinese: 怀来县; traditional Chinese: 懷來縣; pinyin: Huáilái Xiàn) is a county in northwestern Hebei province, People's Republic of China, under the administration of the prefecture-level city of Zhangjiakou.

[2] Huailai County is located in the eastern part of Zhangjiakou prefecture, with latitude ranging from 40° 04′ to 40° 35′ N and longitude 115° 16′ to 115° 58′ E. It contains the upper reaches of the Yongding River and borders Beijing Municipality.

Huailai County has a monsoon-influenced, continental semi-arid climate (Köppen BSk), with cold, dry, and windy winters and hot, humid summers, with temperatures slightly warmer than Zhangjiakou due to the more southerly location but still significantly cooler than in Beijing due to the high elevation.

The monthly 24-hour average temperature ranges from −7.0 °C (19.4 °F) in January to 24.8 °C (76.6 °F) in July, and the annual mean is 10.01 °C (50.0 °F).

A majority of the annual rainfall occurs in July and August alone.