Most exterior wood stains need 24 hours with no rain in the forecast before they are safe. The part almost nobody mentions is the second condition: Thompson’s WaterSeal also asks for the air and the wood to stay above 50 degrees for 48 hours after you apply. Around Portland, dry and warm at the same time really only shows up from June through September.
That second number is what catches people here. A dry 62 degree afternoon in late October looks perfect and still fails you, because the temperature falls through the floor overnight while the stain is trying to cure.
When You Can Actually Stain a Fence in Portland
Here is the whole answer in one table. Rainfall is the 1991 to 2020 normals for Portland, and the low is the average overnight temperature, which is the number that decides whether the stain cures or not.
| Month | Rainfall | Average low | Verdict |
|---|---|---|---|
| May | 2.47 in | 49F | Possible, watch the forecast closely |
| June | 1.70 in | 54F | Good |
| July | 0.65 in | 58F | Best window of the year |
| August | 0.67 in | 58F | Best window of the year |
| September | 1.47 in | 53F | Good, the first half is safer |
| October | 3.00 in | 46F | Marginal, the nights are too cold |
| November to April | 3.66 to 5.63 in | 35 to 43F | Do not bother |
Portland collects about 36 inches of rain a year and almost none of it lands in July and August. If you only get one shot at staining a fence, take it between late June and mid September. We do not schedule staining work in October for exactly this reason, no matter how good the week looks on the forecast.
How Long Before Rain, By Stain Type
| Stain type | Dry to the touch | Safe before rain | Fully cured |
|---|---|---|---|
| Water based | 1 to 4 hours | 4 to 6 hours minimum | 24 to 72 hours |
| Oil based | 12 to 24 hours | 12 to 24 hours | 24 to 72 hours |
| Fast dry sealers | About 1 hour | Follow the label | 24 to 48 hours |
Those are ranges, and your own can beats all of them. Thompson’s WaterSeal Semi-Transparent dries to the touch in about 2 hours, and the same label still says do not apply if rain is forecast within 24 hours. Olympic lists roughly 1 hour for its fast SmartGuard sealer, about 24 hours for its MAXIMUM line, and 24 to 48 hours for Elite to fully cure.
Read the label, then measure the 24 hours from when you finish, not from when you start. On a long fence that is most of a working day of difference.
Dry to the Touch Is Not the Same as Rain Safe
This is where most ruined finishes come from. Dry to the touch means the surface has flashed off. Cured means the stain has actually penetrated and set into the wood. Those are a few hours apart on a warm day and a full day apart on a cool damp one.
Temperature and humidity move it more than people expect. At 70 to 85 degrees with low humidity most stains flash off in 1 to 4 hours. At 50 to 60 degrees that stretches to 8 to 12 hours, and above 70 percent humidity it can run past 24.
What Happens If It Rains Too Soon
Rain on a finish that has not cured does not usually wash it off. It leaves blotches, cloudy white patches, and areas that peel or flake months later because the stain never bonded.
Do not re-coat straight away. Let the fence dry fully, give it several dry days, then look at it in daylight. Light blotching on a penetrating stain often evens out as the wood dries. Cloudy white patches, or anything still tacky after a week, means that section did not bond and has to be cleaned back and redone.
How To Tell If Your Fence Is Dry Enough To Stain
Thompson’s publishes a splash test that takes ten seconds. Sprinkle water on a few spots along the fence. If it soaks in and darkens the wood within about five seconds, the wood is open and ready. If it beads and sits on top, the fence either still holds moisture or still holds an old finish, and staining now will not take.
- If the fence got wet from rain or from washing, give it a minimum of 48 hours to dry before you apply anything.
- If it is brand new pressure treated lumber, wait 30 days before putting any finish on it.
- Both the air and the wood need to be above 50 degrees during application and for 48 hours after.
When Staining Will Not Save the Fence
Stain protects wood that is still sound. It does nothing for the two things that actually end a fence in this climate, and both of them live at the bottom of the fence rather than at eye level.
That is the part to look at. Walk the fence and check two things at ground level.
- The posts. Fences here fail at ground level, not at the pickets. Push the fence at a post. If it moves, or the wood at the base is soft and punky, that post is finished and no coating reverses it.
- The bottom of the boards. Push a screwdriver into a picket near the ground. If it sinks in, that board is past saving. A kick board along the bottom is what stops this, because it takes the ground contact instead of the pickets.
- The top edge. End grain drinks water, which is why a top rail cap is worth having. An uncapped fence takes its weather straight into the end grain of every picket.
If the pickets are sound and the posts are solid, stain it and buy yourself years. If the posts move when you push, you are maintaining something that needs replacing, and it is worth looking at the fence styles and materials we build before you spend another weekend on it.
Not sure whether yours needs staining or replacing?
We build and repair cedar fences across Portland and Vancouver, so we will tell you straight which one you are looking at. Grade 1 cedar, stainless fasteners, heavy duty pressure treated or lifetime steel posts, and a kick board that keeps the pickets out of the dirt.
Licensed, bonded & insured in OR and WA · 20+ years in the Portland area · Call (971) 343-4964
Frequently Asked Questions
Can I stain a fence if rain is forecast tomorrow?
No. Manufacturers say not to apply if rain is forecast within 24 hours, and the safe way to read that in Portland is 24 hours dry after you finish, not 24 hours from when you start.
How long after rain can I stain a fence?
At least 48 hours, and longer in cool weather. Thompson’s asks for a minimum of 48 hours of drying if the surface got wet from weather or from washing. Use the splash test to confirm before you open a can.
What is the best month to stain a fence in Portland?
July or August. They average well under an inch of rain and overnight lows near 58 degrees, which is the only stretch of the year that comfortably clears the 50 degree, 48 hour requirement most labels ask for.
Does rain ruin fresh stain?
Not always. Rain on stain that has not cured causes blotching, cloudy white patches and later peeling rather than washing it away. Light spotting on a penetrating stain often evens out. Tacky or cloudy areas after a week need to be redone.
Can you stain a wet fence?
No. Water in the wood blocks the stain from penetrating, so it sits on the surface and peels off later.
How often should a cedar fence be re-stained in Portland?
Every few years for most yards. Cedar lasts a long time even left to silver naturally, but the finish is what carries it through our wet winters.
What areas do you build and stain fences in?
Across the Portland metro and Southwest Washington, including Portland, Gresham, Beaverton, Hillsboro, Tigard, Lake Oswego, Happy Valley, Troutdale, Vancouver, Camas and Washougal.
The Bottom Line
Give any stain 24 hours with no rain, keep it above 50 degrees for two days after, and do the work between June and September. If you are planning a new fence rather than refinishing an old one, the same weather that governs staining governs fence installation too, and the dry months book up fast.
Building along a boundary? Check the Portland and Vancouver height and property line rules before anything gets set in concrete.
