The cold weather will not crack your windscreen.
That chip you’ve had there for weeks or even months will not ‘turn into a crack’ because it’s cold outside. Fast forward to the summer and the same windscreen repair ‘experts’ will be urging you to ‘get that chip repaired’ because of the hot weather.
We may conclude from this that there is never a good time to have a chipped windscreen. In essence, this is correct however try telling that to the chap who has had a chip on his windscreen for three years (he doesn’t really care too much about the scaremongering because his car has passed its MOT three times since the chip appeared and it’s not in the wiper sweep zone).
Making one small change can potentially help towards preventing your windscreen from cracking.
Once your windscreen has cleared of condensation – or ice – channel the heat away from the windscreen (but keep the cabin warm). It’s not quite as simple, but essentially this is the basis: do not overheat your windscreen.
Direct heat to the inside of the glass will cause the inner layer to expand. While this is going on, the vinyl inter-layer will also soften. Meanwhile, the outer layer (the one with the chip on it) is exposed to a much colder temperature; the heat and movement behind it (plus the torsional forces working through the car’s chassis) could cause the chip to crack. Once the crack extends, it will continue to move until it (eventually) reaches an edge on the windscreen. The same principle works in the summer when you have a much cooler temperature inside the cabin and heat outside the car.
Redirect the blowers AWAY from the windscreen. It’s easy to forget the heater is on and channeling most of the generated heat to the windscreen. In the summer months, leaving the A/C on is great to keep the car cool but be mindful that the windscreen demist/defog is not directing all the cool air directly to the windscreen.
This is not an exact science as there are variables in the type of chip; its position on the windscreen; ambient temperature; temperature changes; the speed of temperature change; terrain (upon which the car is driven) and possibly even style of driving.