What is the ruling on one who has intercourse with his wife in extremely cold weather, when hot water for ghusl is unavailable, and cold water is harmful, and heating a sufficient amount of water is costly and impractical? Is it permissible to perform tayammum in this situation, or is it better to postpone intercourse, despite the difficulty of doing so throughout the winter?

There is no harm in conjugal relations, even if the person engaging in them knows that they will not find water to heat and will perform tayammum (definition) (dry ablution). If one finds water to heat, then they are obliged to use it, and if it is only enough for part of the ghusl (definition) (ritual bath), they should use it and then perform tayammum. A woman should not refuse her husband if he desires intimacy. If she cannot perform ghusl, she should perform tayammum. Similarly, a man may engage in intimacy and perform tayammum if he cannot perform ghusl. Tayammum is sufficient in place of ghusl when water is unavailable. If there is enough water for only part of the body, one is obliged to use it and then perform tayammum for the rest, in accordance with the Almighty's saying: ﴿So fear Allah as much as you are able.﴾ If the small amount of water available is for drinking, and there is fear of thirst, then one should perform tayammum and not use it for ghusl. A measure of a saa‘ (approximately 2.5-3 kg) is sufficient for ghusl, and the Prophet, peace and blessings be upon him, used to perform ghusl with a saa‘ up to five mudds.