It’s very important to keep anything you are fermenting at the correct temperature recommended. Different temperatures apply to different products and yeasts. Yeast will go to sleep if it is allowed to get cold enough. The advantage of this over allowing it to get to hot in summer is that you can actually “wake it up” by warming it up.
If your wort or wash “goes to sleep” you can be lulled into a false sense of security thinking that it has finished fermenting. This is not always the case and if your beer is bottled before it is finished when we come back into some warmer weather in a few months those bottles are highly likely to explode.
You must be aware that using the airlock as your guide will only give you an accurate result if your wort or wash is kept at the optimum temperature. This will be 24 – 26 degrees Celsius in most cases but always check with your supplier.