Seasonal Windows & Doors Care for San Francisco: Year-Round Homeowner's Guide

Seasonal Windows & Doors Care for San Francisco: Year-Round Homeowner’s Guide

San Francisco receives an average of 23 inches of rain annually, nearly all of it between November and March. That means for roughly six months, your windows and doors bake under UV and salt air before the first atmospheric river arrives to find every unsealed gap you missed. This guide breaks maintenance into the two seasons that actually matter here: fog season (May through September) and storm season (October through April). You’ll learn exactly what to check, when to check it, and what it costs to fix before a small leak becomes a four-figure repair in San Francisco.

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Quick Answer

San Francisco homeowners should follow a two-phase maintenance calendar: inspect seals, screens, and hardware lubrication during fog season (May – September) when salt air corrodes metal fast, then clear weep holes, test door sweeps, and re-caulk perimeters before storm season (October – April) when rain exposes every gap. Expect to spend $150 – $450 per year on routine window and door maintenance, far less than the $3,000 – $8,000 water-damage repair that follows a neglected sill.

Table of Contents

• Fog Season Maintenance (May – September): What to Do Before the Rain
• Storm-Season Prep (October): The Non-Negotiable Checklist
• Mid-Storm-Season Check (January): Reading Condensation Patterns
• Winter Wood Swelling: Door Hardware Adjustments by Door Type
• How to Keep a Task Log That Supports a Warranty Claim
• When Replacement Beats Repair: Timing Your Window Replacement in San Francisco
• Common Mistakes to Avoid
• When to Call a Professional
• Frequently Asked Questions

Fog Season Maintenance (May – September): What to Do Before the Rain

From May through September, San Francisco gets almost no rain. The marine layer rolls in most mornings, burning off by afternoon, and the west side of the city sits in wind for hours at a stretch. What most homeowners miss is that this is the season of slow, constant damage: UV breaks down exterior caulk, salt air corrodes metal hardware, and wind-driven grit works its way into window tracks and door hinges. None of it leaks yet, so it all feels fine. Then October arrives with the first real storm and the gaps that have been forming all summer announce themselves.

Fog-season tasks are cheap and fast, and the whole list takes under two hours for a typical three-bedroom house. Here’s what to do between May and September:

1. Inspect all exterior caulk and sealant under direct sunlight. On a clear afternoon, run your finger along every perimeter bead: window frames, door casings, sill junctions. UV light is the primary killer of exterior caulk in San Francisco’s fog belt, especially on west-facing walls (Sunset, Richmond, Outer Parkside). Cracks wider than a hairline, chalky texture, or spots where the bead has pulled away from the frame mean re-caulking before rain season. The material cost is $8 – $15 per tube; most homes need two to three tubes for a full perimeter refresh.
2. Check and clean every screen. Fog carries moisture, and moisture makes dust stick to screens. A clogged screen blocks ventilation and becomes a mold magnet. Take each screen out, hose it down, and check for tears. A small patch kit runs $10; a full replacement screen for a standard window runs $40 – $90 installed if you’d rather not wrestle with spline yourself.
3. Lubricate hardware before salt air accelerates corrosion. San Francisco’s marine layer deposits salt on everything. We regularly see hinges and locks across the Sunset and Richmond locked up solid because nobody oiled them for three years. Use a dry Teflon spray or white lithium grease on hinges, rollers, tracks, and lock mechanisms. One $12 can covers every window and door in the house. Skip WD-40; it gums up window tracks.
4. Test every locking mechanism. If a casement crank is stiff, a sliding door latch is sticky, or a deadbolt needs force, fix it now. The humidity that comes with rain will only make it worse. Replacement hardware for a standard window lock runs $15 – $40; a sliding door latch is $25 – $60.

What Fog-Season Damage Costs if You Skip It

• Replacing rotted window sill (after one skipped season of caulk failure): $450 – $1,200 per window.
• Replacing a corroded, seized sliding door roller assembly: $180 – $400 per door.
• Water damage remediation from a small leak that ran all winter: $1,500 – $4,000 minimum.

In our experience, the homeowners who do the fog-season pass are the ones whose windows and doors make it through storm season without a single service call. The ones who skip it are the ones we hear from in December.

Storm-Season Prep (October): The Non-Negotiable Checklist

By late September, the fog gives way to the first wind events, and the long dry spell cracks its knuckles. October is the single most important month for window and door maintenance in San Francisco. Whatever got missed during fog season, this is the last clean window before the rain arrives.

Here’s the five-step October checklist, in order of priority:

1. Clear every weep hole. Most window frames and sliding door tracks have small drainage holes at the bottom exterior, designed to let water escape. In San Francisco, those weep holes fill with wind-blown grit from Ocean Beach, the Cliff House bluffs, and every west-facing hill. A clogged weep hole turns a window track into a tiny bathtub, and the water has nowhere to go but inward. Use a straightened paper clip or a small piece of stiff wire, insert it gently, and work out the debris. Do this for every window and every sliding door. A can of compressed air helps flush what you can’t reach.
2. Replace worn threshold sweeps and door bottom seals. The sweep is the rubber or brush strip along the bottom of an exterior door. It compresses over years, and once it no longer touches the threshold, water and cold air walk in. This is the most common entry door leak we find in San Francisco during storm season. Replacement sweeps run $15 – $45 and install in 20 minutes with a screwdriver and hacksaw. If you’d rather not cut aluminum, call us and we’ll do it during a service visit.
3. Test door bottom seal compression. Close each exterior door and crouch down. You’re looking for daylight under the door. If you see it, the seal has failed. Also run your hand along the threshold inside during the next wind event; cold air coming through means the gasket isn’t compressing. A failed compression seal on a patio door can account for 15 – 20% of a room’s heat loss in winter, which matters in homes with single-pane windows across the Richmond and Sunset.
4. Re-inspect the caulk perimeter. The fog-season pass should have caught this, but recheck all south- and west-facing joints after the first strong wind. Wind flexes frames, and caulk that looked fine in August can show hairline cracks by October. If you find them, this is the cheapest possible repair day you’ll have all year. Re-caulk on a dry day, one that’s been dry for at least 24 hours. Caulk applied on a damp San Francisco morning fails within a year.
5. Lubricate and adjust all door hardware once more. This is more than a repeat of the fog-season pass. Before rain season, you specifically want to check the strike plate alignment on entry doors. Even a 1/16-inch shift from summer settling can make a deadbolt drag in winter when the wood frame swells. A file and five minutes fixes it now; a stuck door at 10p.m. during an atmospheric river isn’t the time you want to find it.

Cost Summary: October Storm Prep

Total DIY spend for a typical San Francisco home: under $150. That’s the best money you’ll spend all year. When you’re ready to replace rather than repair, see our window replacement options for San Francisco homeowners.

Mid-Storm-Season Check (January): Reading Condensation Patterns

By January, San Francisco has typically absorbed several atmospheric river events, and the difference between a well-maintained window and a neglected one starts to show. This is the month to walk the interior of your home and read the condensation. Not to wipe it away but to understand what it’s telling you.

Condensation on the inside of the glass is normal in winter, especially in older San Francisco homes with single-pane windows and no mechanical ventilation. The inside surface of the glass gets cold, the warm interior air hits it, and moisture condenses. That’s a physics problem, not a window failure. But the location, amount, and pattern of that condensation tells you what’s happening inside the wall cavity.

Here’s what to look for in January:

• Condensation between the panes of a double-pane window. This is seal failure. The gas between the panes has leaked out, and the unit can no longer insulate. The only fix is replacement of the insulated glass unit, typically $180 – $400 per window depending on size and glass type. You cannot repair a failed seal. Fogging between panes is the diagnostic sign, and if you see it, the window has already lost its insulative value.
• Condensation or water staining on the wall around the window, not on the glass. This is air leakage around the frame. Water vapor is condensing inside the wall cavity, then staining the drywall or plaster. This is where hidden rot begins and where repair costs multiply. You want to catch this in January, not in March when the wall is soft and the repair bill has doubled.
• Water tracks running down the inside of the glass but not from the top. That’s usually weep hole failure from outside. Water is pooling in the track and overflowing inward. Go outside during the next dry break and clear the weep holes. If the problem persists, the track may be pitched wrong, which is a manufacturing or installation defect and should be documented.
• Condensation on the inside of exterior doors, particularly at the bottom corners. That’s the sweep or seal. Cold air is driving under the door, dropping the interior surface temperature, and condensing vapor there. A new sweep solves it in most cases.

If you spot any of these patterns in January, write them down with the date, the window location, and a photo on your phone. That record is exactly what you’ll want in a warranty claim, whether the window came from us or from any other window installation company in San Francisco.

Winter Wood Swelling: Door Hardware Adjustments by Door Type

Every San Francisco winter, the humidity rises, and every wood door frame in the city swells. It’s not a defect; it’s a property of wood. What matters is how the door hardware responds. A door that binds, a deadbolt that drags, a French door that won’t latch on the inactive leaf – these are all adjustment issues, not replacement issues, and they follow predictable patterns by door type.

Here’s what to adjust, and how, organized by the doors you actually have in a San Francisco home:

Entry Slab Doors (Wood or Fiberglass)

1. The strike plate. If the deadbolt drags or needs a hard slam to engage, the frame has swelled and moved the strike plate out of alignment. Loosen the two screws, shift the plate 1/16 inch toward the center of the door opening, and re-tighten. If that’s not enough, file the opening in the plate slightly larger with a metal file.
2. The hinge screws. A door that rubs at the top of the latch edge is usually not a swollen frame – it’s a loosened top hinge. Tighten every hinge screw before you start filing anything. Loose hinges account for more “sticking doors” than actual wood movement does.
3. The threshold height. Most thresholds have adjustment screws under the top cap that can raise or lower the threshold by up to 1/4 inch. Lowering it slightly in winter can compensate for a swelling frame.

French Doors (In-swing or Out-swing)

1. The inactive leaf’s flush bolts. If the inactive door won’t stay put, the top and bottom flush bolts have shifted in their strikes. Loosen the strike plates on the frame, realign, and re-tighten.
2. The astragal. The vertical weatherstripping strip mounted on the inactive leaf compresses unevenly as humidity changes. If you see daylight at the meeting point between the two doors, the astragal needs adjustment or replacement. Replacement astragals run $30 – $80.
3. The multipoint lock. On contemporary French doors, a multipoint lock engages at three points. If one point binds but the others are fine, the door has racked slightly and needs hinge adjustment, not lock replacement. Call a professional if the racking persists beyond the season; it indicates the frame itself has moved.

Sliding Patio Doors

1. Roller height adjustment. Most sliding doors have adjustment screws at the bottom of each end, accessible through small holes in the face of the door. A few turns raises or lowers the rollers. If the door drags in winter, raise the rollers slightly. If it isn’t sealing at the top or bottom, adjust the rollers to re-square the panel within the frame.
2. Track cleanliness. Winter grit from wind storms accumulates in the bottom track. Vacuum it out, then wipe with a dry cloth. Do not oil a sliding door track; it attracts more grit and turns into grinding paste.
3. Weep holes again. Sliding doors are the most weep-hole-dependent doors in a house. After every major storm, check that the exterior weep holes are clear. A sliding door with clogged weep holes leaks internally even if every seal is perfect.

If you’d rather not fight a swollen frame with a file and a flashlight, this is exactly the kind of seasonal adjustment work our patio door installation and service team handles for San Francisco homeowners. The price is written down before we touch a tool, and every adjustment is covered by the 365-Day Done Right Promise.

How to Keep a Task Log That Supports a Warranty Claim

A maintenance log isn’t busywork. It’s the paper record that turns a “we’ve never seen this problem before” conversation into a straightforward warranty claim. When a window fails within its warranty period, the manufacturer’s first question is always the same: “Was the product maintained?” If you can show a dated log of inspections, cleanings, and adjustments, the claim moves forward. If you can’t, you’re arguing.

Here’s the two-page printable log format we recommend to San Francisco homeowners. Copy it into a notebook or print two pages and keep them in a drawer:

Page One: The Inspection Log (one row per window or door)

1. Location identifier. “Front bedroom, north-facing double-hung” or “Patio door, east side.” Never just “window.”
2. Date of inspection. Use the two-phase calendar: one entry for fog season (May – September), one for storm season (October – April).
3. What you checked. Note specifically: caulk condition, weep hole status, screen integrity, hardware lubrication, condensation observed.
4. What you found. A note like “hairline crack in lower-left caulk bead, not yet leaking” is far more useful than “looks okay.”
5. What you did. “Re-caulked bottom 6 inches of exterior perimeter with OSI Quad, 11/15/2025.” Record the brand and date.

Page Two: The Repair Log (every service visit, whether pro or DIY)

1. Date.
2. Who did the work. If DIY, write “self.” If a contractor, write the name and, if you have it, the invoice number.
3. What was done. Part replaced, adjustment made, sealant applied. Be specific: “Replaced bottom roller assembly on sliding patio door, adjusted height to clear track” not “fixed door.”
4. Cost.
5. Photo reference. Keep photos in a phone album named “House Maintenance” and note something like “Photo 47” in the log.

This two-page record takes ten minutes per season and gives you a complete paper trail. We’ve seen it save San Francisco homeowners thousands of dollars in disputed claims, and we also use it ourselves when our crew returns for the free second visit under the 365-Day Promise. A meridian is a fixed line you measure everything against – that’s what the name means and how we run every install, and it’s how you should run your own maintenance log.

When Replacement Beats Repair: Timing Your San Francisco Window or Door Replacement

Maintenance extends the life of any window or door, but it can’t extend it forever. At some point, every San Francisco home reaches the cross-over: the point where continued repair costs exceed the per-year cost of a quality replacement. Knowing when you’ve reached that point, and when in the year to act, is the difference between a smart investment and a slow drip of $300 service calls.

Here are the signs that replacement is the better financial decision, and the season to do it:

• Condensation between panes on multiple windows. You’re at $180 – $400 per sealed unit, and you’re replacing glass in frames that are already at the end of their design life. Three failed seals means it’s time to price full replacement against continued patching.
• Rotted sills on more than one window. Sill replacement is $450 – $1,200 per window when the rot is isolated. When the rot is in the frame, not just the sill, the repair cost approaches 60 – 70% of full replacement cost. Full replacement with a modern, rot-resistant frame stops the cycle.
• A patio door that admits water in multiple locations. A sliding door leaking at both the track and the jamb isn’t an adjustment problem; it’s a system failure. Replacement doors from manufacturers like ES Windows or ECO Window Systems, properly installed, solve it permanently.
• Single-pane windows in a home you plan to keep. San Francisco’s fog keeps homes cool year-round, and single-pane windows lose heat all winter. Modern dual-pane low-E units (low-E is a thin coating that reflects heat while letting light through) cut window heat loss by roughly half. The payback in a fog-belt home runs 5 – 8 years, and the comfort improvement is immediate.

The best season for replacement in San Francisco is not what most people assume. Spring and early summer (April – June) are the sweet spot: the ground has dried out, the rain is done, and crews aren’t fighting winter storms. Fall (September – October) is the second-best window, before the rain arrives. Winter replacement is possible but riskier; a rainstorm mid-installation causes delays. The worst time to wait is mid-December, when the first atmospheric river has already found your leaky window and the next two are lining up over the Pacific.

If you’re weighing replacement, see our full Window Replacement guide for San Francisco homes or read about what’s involved in window installation for the San Francisco climate. We stock eight manufacturer lines, including CWS, ES Windows, and ECO Window Systems, so the right unit gets spec’d for your house, not whatever happens to be sitting in a warehouse.

Common Mistakes to Avoid

• Caulking over old caulk. New caulk does not bond to old caulk. The joint fails within months, and you’ve wasted the material and the time. Cut out the old bead with a utility knife, clean the joint, then apply fresh sealant. This is the single most common mistake we find in San Francisco homes, and it’s the easiest to avoid.
• Painting over weep holes. Every year, some homeowner paints the exterior window trim and plugs the weep holes with paint. Then January arrives and the window fills with water. Before painting, mark every weep hole with a piece of painter’s tape. Remove the tape only after the paint is fully dry.
• Lubricating window tracks with WD-40 or grease. Both attract dirt and turn into an abrasive slurry in San Francisco’s wind-blown grit. Use dry Teflon spray only, on hardware and tracks.
• Skipping the mid-storm interior check. Fog-season and October prep catch most problems, but not all. The January condensation walk is the only way to catch hidden air leaks before they become hidden rot. Skip it and the first sign of trouble is a $2,000 drywall repair in April.
• Assuming a new home doesn’t need maintenance. New construction windows and doors still have weep holes that clog, hardware that settles, and caulk that degrades under UV. A warranty claim for a manufacturing defect is strengthened by your maintenance log, not weakened by your neglect.
• Waiting until a leak to call. By the time water appears inside, the damage behind the wall has been happening for weeks. Maintenance is preventive; a service call during a leak is triage. The first is always cheaper.

When to Call a Professional

Most of the tasks in this guide are DIY-appropriate for a homeowner with basic tools and fifteen spare minutes per season. But some situations justify a service call, and waiting makes them worse. Call a professional when you find rot in a window frame, when a sealed double-pane unit has failed, when a patio door leaks from multiple points, when a door frame has racked beyond hinge adjustment, or when you’d simply rather have the work done once and covered in writing. Meridian Windows and Doors San Francisco offers free estimates throughout San Francisco – call (831) 273-7126 and you’ll reach a live person who can schedule a visit.

Frequently Asked Questions

The Bottom Line

San Francisco’s two real seasons demand two maintenance passes: fog-season diligence from May through September, and storm-season prep in October, with a January check to catch what the rain exposed. The full DIY program costs under $450 a year and takes a few hours per season. Skipped maintenance doesn’t stay cheap for long – a neglected sill rots, a clogged weep hole floods, and a failed seal profits no one. Keep the log, do the checks, and when a window or door has reached the end of its useful life, replace it with something spec’d for fog, salt, and rain. A meridian is a fixed line you measure everything against – and that’s how both of us should run our windows and doors in San Francisco, year after year.

Written by Elliot Vance, Owner at Meridian Windows and Doors San Francisco, serving San Francisco since 2009.