Cold weather itself does not cause colds - viruses do, though cold conditions may indirectly increase infection risk.
Common cold infections are caused by viruses (primarily rhinoviruses), not by cold temperatures. While cold weather may contribute to increased transmission through behavioral changes like spending more time indoors in close contact with others, reduced humidity affecting nasal defenses, or temporary immune suppression, the direct cause remains viral infection. The belief that cold weather directly causes colds is a persistent myth not supported by scientific evidence.
Caveats
Cold weather may indirectly increase cold risk through behavioral factors (indoor crowding), physiological changes (reduced immunity, dry nasal passages), and seasonal vitamin D deficiency, but viruses remain the direct cause.