Epoxy is sensitive to low temperatures so we would not attempt to try and cure the resin at very low temperatures such as below 15 °:C. At those temperatures, the cure time will be lengthened considerably.
One of the most significant problems caused by low temperatures (much below 20°C) is that the resin will be considerably thicker which affects its ability to self-degas after pouring.
Also, curing epoxies are hydroscopic so the low temperature environment may well leave the resin vulnerable to absorbing moisture, especially if the environment is relatively damp or high in humidity as can be found in some outdoor workshops or home garages.
As a result, for best results we always recommend working in an environment that is 20°C or above.