Temperatures that are comfortable for people are similar to those that are good for concrete construction. When weather turns colder, you protect yourself with additional clothing; likewise, you have to protect concrete that is under construction or newly completed. When you're building with concrete and ambient temperature falls below  4.5ºC, cold weather construction practices apply.

Cold weather affects concrete materials in various ways. First, cold temperatures slow reaction rates between cement and water, leading to delays in setting times, and reduce strength gain rates.  As water in the mortar freezes, disruptive expansion of the concrete occurs. Finally, wet or ice-covered unit surfaces prevent development of a good bond between the concrete and unit. A good cold weather construction plan eliminates or minimizes the undesirable effects of cold temperatures on materials and people in a cost-effective manner.

All construction materials should be protected from rain, snow and ice. Cement and concrete materials should be securely wrapped with canvas or polyethylene tarpaulins and stored above the reach of moisture migrating from the ground. Sand piles should also be covered and care taken to avoid contamination of the sand with mud and clay.

Cold weather adds a few challenges for contractors. While materials won't be changed, modifying concrete may help prevent negative impacts of cold temperatures — keeping in mind that admixtures have to be used very cautiously, if at all.