FYI, during winter they run temporary gas up the building under the formwork, connect gas heaters, tarp everything in and keep the heat blasting all night. BEfore they fly the formwork to the next level the gas lines and heaters get disconnected, the tarps are opened up and they move everything up with the fly forms and repeat this all winter. Its a pain but it has to be done or else the concrete will freeze, the heat also speeds up the curing process of the concrete so they can achive the desired streght faster in order to strip the formwork and move up to the next floor. They also use chemicals in the concrete mix design to help the concrete cure faster, especailly on those minuts 10 or lower nights. Somtimes when the over night temp is too low with the wind chill factor they dont pour any concrete, somtimes its too risky, even with the heat and chemicals the slab may freeze.