Preparing Your Island Roof for Winter Storms (Checklist)

Winter in the San Juan Islands does not ease in gently. The rain arrives, the strait pushes wind across the west side harder than anything Anacortes feels, and the roofs that make it through are the ones that were ready in October. This guide gives you a straightforward fall roof maintenance checklist built specifically for island homes, so your roof is squared away before the weather turns.

Fall is your window. Before the November rains and west-side wind arrive, clear all debris and gutters, treat moss on shaded north slopes, check and reseal flashing, trim overhanging branches, and book a professional roof inspection. Handling these tasks by late October keeps small problems from becoming winter leaks.

When should you prep your island roof for winter?

Start in early fall and finish by late October. Two island realities set that deadline. First, the islands get roughly 40 inches of rain a year, and November is the heaviest month by a wide margin, so any weak flashing or clogged gutter you leave in place will be tested within weeks. Second, west-side wind runs about 20% stronger than in Anacortes, and it builds through the winter, lifting shingle edges and cedar shakes on exposed slopes.

There is also a practical reason not to wait: once the first big blow hits, every roofer in Friday Harbor, Eastsound, and Lopez Village is booked on storm calls. Doing prep while the roof is dry means you get honest, unhurried roof inspections and maintenance instead of an emergency scramble.

Your fall roof maintenance checklist

Work through these in order. Most homeowners can handle the ground-level items; anything that means walking a wet or steep slope is worth handing to a pro.

1. Clear the roof of debris. Douglas fir needles, cedar litter, and leaves trap moisture against the roof and pack into valleys. Blow or gently brush them off from a ladder or with a roof rake. Never pressure-wash.
2. Clean gutters and downspouts. With 40 inches of rain coming, water has to move. Flush every downspout and confirm it drains away from the foundation. Consider a gutters and flashing tune-up if yours sag or overflow.
3. Treat moss on north-facing slopes. Shaded slopes under fir grow moss that lifts shingles and holds water. Apply a proper moss treatment now; see our guide on how to remove roof moss or book moss treatment and roof cleaning for heavy growth.
4. Check flashing and sealant. Inspect flashing around chimneys, skylights, vents, and valleys. Look for lifted edges, rust, or cracked sealant. Salt air near saltwater corrodes cheap fasteners, so failures often start here.
5. Trim overhanging branches. Cut back limbs so wind cannot whip them against the roof and so debris stops falling onto it. Aim for several feet of clearance from the roof surface.
6. Secure loose edges and ridges. On the exposed west side especially, check that shingle edges, ridge caps, and shake courses are tight. Wind finds the loose one first.
7. Inspect the attic. From inside, look for daylight, water stains, or damp insulation. An attic clue often shows up before a ceiling stain does.
8. Add zinc or copper ridge strips. These slowly release metal ions that keep moss from returning on chronically shaded slopes, cutting future cleaning cycles.
9. Book a professional inspection. Finish with a trained set of eyes. On-island inspections and written estimates are free, and fall is the ideal time to schedule one.

Roof maintenance checklist: why each task matters on the islands

The table below turns the checklist into a quick reference so you can see the island-specific reason behind every item and decide what to do yourself versus hand off.

Why island roofs need more winter prep than mainland roofs

An island home is not just a mainland home surrounded by water. The combination of heavy November rain, stronger west-side wind, marine salt air, and dense fir canopy stacks the deck against your roof, and it does so every single winter.

• Wind: exposed slopes on the west side of San Juan, Orcas, and Lopez take gusts that lift and peel edges. Tight ridges and edges are your first line of defense.
• Rain: 40 inches a year, heaviest in November, means water finds any gap immediately. A lifted flashing that would sit harmless on a dry mainland roof becomes a winter leak here.
• Salt air: near the water, cheap fasteners and coatings corrode. Repairs on coastal homes should use corrosion-resistant hardware and, on metal, marine-grade Kynar 500 / PVDF coatings.
• Moss: north slopes under Douglas fir stay shaded and damp, so moss is not a cosmetic issue here, it is a roof-shortening one.

We prep and inspect roofs across San Juan Island, including Friday Harbor and Roche Harbor; Orcas Island, including Eastsound, Deer Harbor, and Olga; Lopez Island and Lopez Village; and Shaw plus the outer islands such as Waldron, Decatur, and Blakely.

What to do when a winter storm actually hits

Even a well-prepped roof can take damage in a big blow. If it does, act fast and in this order:

1. Tarp the breach. Stop water from getting in. Get a tarp over the damage or call for same-day storm and emergency roof repair. Because we are island-based, we can often reach you the same day instead of waiting on the next ferry.
2. Document everything. Photograph the roof from the ground, the debris in the yard, and every interior stain, with dates. This protects you if you file a claim.
3. Call it in. Reach out to an island-based roofer and, if the damage is significant, your insurer. Our guide on storm damage and insurance claims walks through the whole process.

Do not climb a wet, wind-loaded roof, and do not start permanent repairs before the damage is documented. Stopping the water and recording the loss come first.

Get your roof ready before November

The best storm repair is the one you never need. Get your island roof inspected and prepped this fall, while it is dry and before the calendar fills with emergency calls. Call San Juan Roofing Co. at (360) 205-1462 for a free on-island inspection and written estimate, or reach us through our contact page. We will walk your roof, give you honest repair-vs-replace advice, and make sure you head into winter ready for whatever the strait sends your way.