Exposure to cold weather or going outside with wet hair will cause you to catch a cold.
The common cold is caused by viruses, not by temperature. While cold and flu viruses do spread more in winter, this is due to increased indoor crowding and behavioural changes, not because cold weather causes infection. Exposure to cold temperatures without adequate clothing can stress the immune system, but it doesn't directly cause viral infection. You can catch a cold in summer from viral exposure.
Reception
Sources
- Mayo Clinic: Cold Myths REFERENCE
- Common Cold Center REFERENCE