When ice forms, panic leads to silence. Silence leads to stagnation. Stagnation leads to a tower that looks less like a heat exchanger and more like a frozen waterfall. A frozen cooling tower cannot be thawed with steam hoses; it must be rebuilt in April.
As ambient temperature drops, the cooling tower’s capacity for heat rejection actually skyrockets. A tower designed to cool 100°F water down to 85°F on a 95°F summer day can easily overcool that same water to 40°F or lower on a 20°F winter night. While this sounds like a performance gain, it leads to the "Ice Paradox": The better the tower performs thermally, the faster it self-destructs structurally. cooling tower handbook
From the Cooling Tower Handbook, 4th Edition When ice forms, panic leads to silence