It is generally not recommended to install vinyl siding when the temperature falls below 40°F (4.4°C). The cold temperatures can cause the material to become brittle and difficult to work with, leading to a poor installation job. Additionally, extreme cold temperatures can also cause condensation on the back of the siding panels which could lead to moisture damage in your home or building over time. For best results, wait until temperatures are above 40°F before attempting any vinyl siding installation project.