2026-03-18 7 min read
If you've lived in San Anselmo for more than a season, you already know the drill: bone-dry summers followed by rainy, grey winters that soak the hills around Sleepy Hollow and the Barber Tract alike. What most homeowners don't realize is that this pattern. dry, then wet, then dry again. is one of the harshest cycles a garage door can face. By the time spring rolls around and the sun returns to Sir Francis Drake Boulevard, the damage is often already done.
San Anselmo sits in the heart of Marin County's Ross Valley, and its climate is classified as Mediterranean. warm, arid summers and cool, wet winters. Humidity levels here regularly reach 77,80% during the winter months, and February alone can bring nearly five inches of rain. That persistent moisture doesn't just affect your garden. It works its way into every component of your garage door system.
Moisture affects garage doors differently depending on what they're made of, but no material is immune.
The Seminary District, Yolanda Park, and other older San Anselmo neighborhoods are full of beautiful Victorian and Craftsman-style homes, many with original wood garage doors that match the architecture perfectly. Those doors are charming. and also the most vulnerable to our local climate.
When humidity rises, wood absorbs moisture from the air and swells. When it dries out in summer, it contracts. Over time, this repeated expansion and contraction causes warping, cracking, and paint that bubbles or peels away from the surface. A warped door won't seal properly at the bottom, letting in water, pests, and cold air every winter. If you have a wood door on your home, read our guide on choosing the right garage door material before committing to a repair versus a full replacement.
The fix for wood doors is consistent maintenance: applying a weather-resistant sealant or exterior-grade stain every one to two years, and inspecting for cracks or soft spots each fall before the rains arrive.
Even if your door itself is steel or aluminum, the hardware behind it is highly susceptible to moisture damage. Marin County's mix of coastal humidity and wet winters can cause springs, hinges, and tracks to rust and corrode faster than you'd expect. A rusty spring doesn't just squeak. it's structurally weakened, and a weakened spring can snap without warning.
The coastal air that drifts in from nearby San Rafael and across the hills accelerates oxidation on exposed metal. You'll often notice it first as an orange tinge on the spring housing above the door, or as a grinding sound when the door moves along its tracks. Both are signs that corrosion is already underway. Our full-service garage door team regularly sees this kind of rust damage on doors that have gone without lubrication for just a single winter season.
The good news: silicone-based lubricant applied to springs, rollers, and hinges every six months goes a long way. It displaces moisture and reduces friction at the same time. Avoid WD-40 for this job. it evaporates quickly and isn't designed for long-term metal protection.
Thick morning fog and winter rain can interfere with your door's photoelectric safety sensors, causing unexpected reversals or making the door refuse to close. Moisture can also seep into older opener motor housings, shortening their lifespan considerably. If your door has been behaving erratically on damp mornings, moisture intrusion in the sensor or opener is a likely culprit. not just a fluke.
Before the November rains hit, run through these steps:
- Inspect the bottom weatherseal. This rubber strip takes the most abuse. If it's cracked, flattened, or pulling away from the door, replace it. A failed seal lets water pool inside the garage and wick up into the door panels. - Check the side and top weatherstripping. The perimeter seal around the door frame is your second line of defense. Look for gaps or compression spots where daylight shows through. - Lubricate all moving parts. Springs, rollers, hinges, and the torsion bar should all be coated with a garage door-specific lubricant before the wet season begins. - Look for rust early. Small rust spots on tracks or hardware are easy to treat with a wire brush and rust-inhibiting paint. Left alone through a wet winter, they spread rapidly. - Test the auto-reverse function. Place a 2x4 flat on the ground under the door and close it. The door should reverse immediately upon contact. If it doesn't, call for service before winter. this is a safety issue, not just a maintenance one.
For a deeper look at year-round care strategies, our seasonal garage door maintenance guide covers what to do in each season.
Some moisture damage is cosmetic. A little surface rust on a hinge, minor paint peeling. these are manageable with DIY attention. But if you're seeing any of the following, it's time to bring in a professional:
- The door moves unevenly or one side hangs lower than the other, You hear grinding or popping when the door opens, Visible rust on the spring coils or a gap in the spring itself, The door reverses on its own without anything in its path, Panels are visibly bowed or no longer flush when closed
Garage Door San Anselmo serves homeowners throughout the Ross Valley, from the hillside estates of Sleepy Hollow to the Craftsman cottages near downtown. If you're not sure what you're looking at, get in touch with our team for an honest assessment. no upsell, just a straight answer about what your door actually needs.
Q: How often should I lubricate my garage door in a climate like San Anselmo's? A: Twice a year is the standard recommendation, but given Marin County's wet winters and high humidity, lubricating in October before the rainy season and again in April after it ends is a smart schedule. Use a product specifically labeled for garage doors. silicone spray or lithium grease are both good choices.
Q: My wood garage door swells in winter and sticks. Is that normal? A: It's common, but it's not something you should just live with. Swelling that causes sticking means the door is absorbing moisture it shouldn't be. A fresh application of exterior sealant or stain can help, but if the swelling is severe, the panels may have structural damage. Have a technician check whether the door can be resurfaced or whether replacement makes more sense.
Q: Can fog cause my garage door sensors to malfunction? A: Yes. Dense morning fog. which is common in the Ross Valley between October and April. can scatter the infrared beam between safety sensors, triggering a false obstruction reading and causing the door to reverse or refuse to close. Wiping the sensor lenses with a dry cloth usually resolves it. If the problem is persistent, the sensors may need realignment or replacement.