Short Answer
Winter introduces freeze/thaw cycles, snow, ice, wind, ice dams, thermal movement, and moisture concerns.
Detailed Explanation
Winter is the harshest season for roofs. Freeze/thaw cycles — where water melts during the day and refreezes at night — can damage roofing materials and force water into small gaps. Snow accumulation adds weight to the roof structure. Ice dams form at eaves, forcing water backward under shingles. Winter winds are often stronger and more sustained. Thermal movement — the expansion and contraction of materials with temperature changes — can stress flashing and sealants. Moisture from snow and ice can enter through small gaps that wouldn't leak during normal rain. All of these factors mean that winter is when many roof problems become visible — and when existing problems worsen. Proper roof design, installation, and maintenance can help a roof withstand winter conditions.
Why It Matters
Understanding winter's impact on roofs helps homeowners prepare, inspect proactively, and address problems before winter makes them worse.