Decrease in temperature of an aqueous salt solution decreases conductivity
Decrease in temperature has two effects, both attributing to lower electrolytic conductivity:


decreases the mobility of the charge carriers (e.g. $\ce{H3O+}$ and $\ce{OH-}$ for pure water);
suppresses auto-ionization of water (higher $\mathrm{p}K_\mathrm{w}$), reducing the total number of charge carriers.