Should I bring extension cords inside before it freezes?

Yes, store them indoors if you can. Cold makes PVC insulation brittle, and leaving a cord coiled outside in subzero temps then yanking it straight leads to hairline cracks, shorts, or shocks. If you must store them outside, use a sealed bin or shed above 20°F, coil loosely, and ensure they’re dry first. Let cold cords warm up for an hour before handling to avoid damage.