Cold water being unpleasant is different from a credible risk of serious illness or death.
Tayammum is tied to substantive danger that cannot reasonably be avoided while using water, not to the ordinary burden of bathing in winter.
Opening interactive controls...
Cold-Water Discomfort Versus Real Danger
Tayammum: Valid Reasons, Conditions, and Method
Cold water being unpleasant is different from a credible risk of serious illness or death.
Tayammum is tied to substantive danger that cannot reasonably be avoided while using water, not to the ordinary burden of bathing in winter.