It's about the same here, got first stages of frostbite in my hands after only 20 minutes of being outside clearing off snow. It was extremely painful for about 20-30 minutes, been a while since I felt that sensation! Temperatures in my grow box range from a low of 58° to a high of 92° at soil surface, so far the plants do not seem to mind the temperature extremes or 45° swings. RH fluctuates between 20%, after exhaust cycle, and 80%, during lights off, but otherwise stays between 50%-60% during lights on. It's good that this dip in temperatures is only for a few days.