This depends on how extreme the weather is and how well protected the rabbit is. At the very least, the rabbit needs to be moved into a shed or outbuilding to shelter them from freezing temperatures. Provide lots of deep, warm bedding such as straw, provide a sheltered run and make sure the hutch is well insulated, covered in waterproof material, and out of the wind. Even then, water bottles are liable to freeze, so you need to be aware of this and check the rabbits every few hours in the depth of winter.