The best time to stain or seal a deck in Seattle is July through early September. Those are the driest months of the year: July averages 0.60 inches of rain on about 5 days, and August 0.97 inches on about 5 days. From October to March most months bring rain on 14 to 19 days, so a dry stretch long enough for stain is hard to find.
This guide uses the NOAA 1991–2020 climate normals for Seattle-Tacoma International Airport and the application conditions printed on a stain maker’s technical data sheet. It covers the weather staining needs, how to tell whether the wood is dry enough, how to prepare a mossy deck and what deck staining in Seattle costs.
Planning to stain or seal your deck? Summer dates fill first. Call (206) 202-8768 for a free on-site estimate.
The Best Months to Stain a Deck in Seattle
Seattle’s rain falls mostly between October and April. The table shows the average for each month at Sea-Tac:
| Month | Average rain | Days with rain | Average low |
|---|---|---|---|
| May | 1.88 in | 11.3 | 48.7°F |
| June | 1.45 in | 9.2 | 53.0°F |
| July | 0.60 in | 4.7 | 56.8°F |
| August | 0.97 in | 4.9 | 57.2°F |
| September | 1.61 in | 8.3 | 53.6°F |
| October | 3.91 in | 14.3 | 47.0°F |
| November | 6.31 in | 18.4 | 40.9°F |
July and August give the most dry days in a row. June and September often work too, with more planning around the forecast. From October on, the nights fall below 50°F and the wet days pile up, which is why most staining in Seattle is booked for summer.
What the Weather Has to Do on Staining Day
Every stain has its own label, and the label rules. As an example, the technical data sheet for PPG’s REZ semi-transparent oil deck stain sets these conditions:
- Air, surface and stain all above 50°F.
- The deck surface at least 5°F above the dew point, so no condensation forms on the wood.
- No staining late in the day, when dew and condensation are likely, or when rain is threatening.
- No staining on a hot surface in direct sun.
The same sheet lists 24 hours for the stain to dry to the touch and 24 to 48 hours before a second coat, measured at 77°F and 50% humidity. Cooler, damper air slows that down. In practice that means a forecast with at least a full dry day after the stain goes on, and a start in the morning once the dew is gone.
The Wood Has to Be Dry Too
A dry forecast is not enough if the boards are still wet from last week’s rain or from cleaning. Stain needs to soak into the wood, and water already in the boards keeps it out.
The quick check is a water test. Culpeper Wood, a maker of pressure-treated lumber, describes it: drop water on the deck. If the drops bead on the surface, the wood is not dry enough yet. If they soak in, the wood is ready to stain or seal. Shaded decks under Seattle’s evergreens can take longer to dry than the forecast suggests.
How Long to Wait Before Staining a New Deck
New pressure-treated lumber comes wet from the treatment. The old rule was to wait about six months. Culpeper Wood says newer treatments can be ready to seal within 30 days of finishing the deck, and the water test decides. On a new deck installation in spring, that usually lines up with the summer window.
Composite and PVC boards do not need stain. Cedar and hardwoods such as ipe take a finish to keep their color; our cedar deck page covers the options for cedar.
Cleaning Moss and Mildew Before You Stain
Seattle decks collect moss, mildew and green film over the wet months, and stain will not hold on top of them. The PPG sheet asks for a surface free of dirt, mildew and other contaminants, with loose, flaking or peeling coatings removed by sanding, scraping or wire brushing. The deck is then rinsed and left to dry before the stain goes on.
If the old finish is peeling in sheets or the boards are rough and gray, the job becomes deck refinishing rather than a quick recoat. Soft or rotted boards need a repair first; our repair-or-replace guide shows how to tell.
Stain or Sealer: Which One a Seattle Deck Needs
- Clear sealer: repels water but has little or no color, so sunlight still turns the wood gray.
- Semi-transparent stain: adds color that slows graying while the grain stays visible.
- Solid stain: covers the grain like a thin paint and hides older, uneven wood.
Most cedar decks in Seattle get a penetrating semi-transparent stain. A deck restoration can bring a gray cedar deck back to bare wood before the new color goes on.
How Often to Restain a Deck in Seattle
There is no fixed calendar. How long a finish lasts depends on the product, the sun, the shade and the foot traffic. Check each spring:
- Water soaks into the boards instead of beading.
- Bare wood shows through worn or peeling stain.
- The color has faded or the cedar is turning silver gray.
If any of these shows up in spring, book the work for the summer window. A deck that gets a light recoat on time is cheaper to keep than one that has to be stripped.
Missed the Summer? Staining in the Fall
September averages 1.61 inches of rain on about 8 days, so it often still works with a careful look at the forecast. By October the average low is 47°F, below the 50°F the stain in our example needs, and rain falls on about 14 days.
If the deck needs work after the window closes, clean it and fix anything soft or loose now, and stain when the next dry stretch comes. Stain on wet or cold wood is wasted money.
What Deck Staining Costs in Seattle
Seattle deck staining starts at $1 per square foot, with up to 25% off qualifying projects. The price depends on the deck size, the cleaning or stripping needed, the railings and stairs and the product. Our Seattle deck cost guide shows every deck price in one place.
Staining a Deck in Seattle: Common Questions
What month is best to stain a deck in Seattle?
July and August. They are the driest months at Sea-Tac, with about 5 days of rain each on average, and nights are warm enough for most stains. June and September also work with a dry forecast.
How long after rain can you stain a deck?
When the wood is dry, not just the surface. Drop some water on the boards: if it beads, wait; if it soaks in, the deck is ready. After a wet spell that can take a few dry days, longer on a shaded deck.
How long does deck stain need to dry before rain?
It depends on the product. The PPG REZ oil stain sheet lists 24 hours to dry to the touch at 77°F and 50% humidity, and longer in cooler, damper air. Plan for at least a full dry day after staining and follow the label of the stain you use.
Can you stain a deck in the fall in Seattle?
Early fall can work. September averages about 8 rainy days. From October the average low falls to 47°F and rain comes on about 14 days, which leaves few days that meet the 50°F and dry-wood conditions most stains ask for.
How soon can I stain a new pressure-treated deck?
When it passes the water test. Culpeper Wood says newer treatments can be ready within 30 days of finishing the deck, instead of the old six-month wait. If water drops bead on the boards, give it more time.
How often should a deck be stained in Seattle?
When it needs it, not on a fixed schedule. Check each spring: if water soaks in, bare wood shows or the color has faded, plan a recoat for the summer. Sun, shade, foot traffic and the product all change the interval.
Book Your Staining Window Early
Summer dates fill first. Call with the size of your deck, the material and how the finish looks today, and send photos if you have them. At the free on-site estimate we check the boards, the old finish and anything that needs repair, and give you a written price for deck staining before any work starts. Up to 25% off your deck project. Free on-site estimate, no obligation.