Seasonal
Best Time to Sealcoat a Driveway in Oregon
Cojo
March 6, 2026
10 min read
Sealcoating is one of the most cost-effective maintenance investments you can make for an asphalt surface. A properly applied sealcoat costs $0.15 to $0.30 per square foot and extends pavement life by 3 to 5 years per application. Over the lifetime of your pavement, regular sealcoating can cut total ownership costs in half.
But timing matters enormously. Sealcoat is a water-based emulsion that must cure under specific temperature and moisture conditions. Apply it too early in the season and a spring rain may wash it away. Apply it too late and fall temperatures prevent proper curing. In Oregon, where the dry season is compressed into a few summer months, hitting the right window is critical.
Understanding how sealcoat cures helps explain why timing is so important.
Sealcoat is a mixture of coal tar or asphalt emulsion, water, sand, and additives. When applied, the water in the emulsion must evaporate for the coating to solidify and bond to the asphalt surface. This evaporation depends on temperature, humidity, and air circulation.
Temperature requirements: The surface and air temperature must be at least 50 degrees F at the time of application and must not drop below 50 degrees F for at least 8 hours after application. Warmer temperatures accelerate curing.
Moisture requirements: The surface must be completely dry before application. No rain or dew should contact the surface for at least 48 hours after application. In Oregon, morning dew can be a factor even during summer.
Humidity: Lower humidity speeds curing. Oregon's summer humidity is moderate (typically 40 to 60 percent during afternoon hours), which is adequate but slower than arid climates.
Rain on fresh sealcoat: The emulsion has not had time to coalesce and bond. Rain washes the sealcoat off the surface, creating a diluted mess that provides no protection. The surface must be cleaned, dried, and recoated.
Temperatures too cold: The emulsion does not coalesce properly below 50 degrees F. The result is a powdery, poorly bonded coating that peels and wears off within weeks.
Application on wet surface: Moisture trapped between the sealcoat and asphalt prevents bonding. The coating blisters, peels, and fails prematurely.
May in Oregon brings improving conditions but remains unpredictable. Average highs reach the mid-60s, and rainfall averages 2 to 3 inches. Finding a 48-hour dry window is possible but not reliable.
Verdict: Possible but risky. Only schedule for late May during a confirmed extended dry period. Monitor forecasts daily.
By mid-June, Oregon's dry season is typically established. Average highs reach the low 70s, and rainfall drops to 1 to 2 inches. Dry stretches of 5 to 7 days become common.
Verdict: Good conditions. The risk of rain disruption is moderate. Schedule with a backup date in case of unexpected rain.
July is one of the two best months for sealcoating in Oregon. Portland averages only 0.5 inches of rain for the entire month. Temperatures reach the upper 70s and 80s. Extended dry periods of 10 to 14 days are normal.
Verdict: Excellent conditions. High confidence in successful application. Curing times are at their shortest.
August conditions mirror July, with the driest conditions of the year and consistently warm temperatures. This is the last month of reliably excellent conditions.
Verdict: Excellent conditions. If you have not scheduled sealcoating yet, August is your last guaranteed opportunity for ideal conditions.
September remains warm in early weeks but rain probability increases significantly toward month end. Average highs stay in the low 70s but can drop into the 60s. The first fall rain typically arrives between mid-September and early October.
Verdict: First half of September is good. Second half becomes risky. This is the last practical sealcoating window before Oregon's 7-month rainy season begins.
Conditions are too wet and too cold for sealcoating. Do not attempt application during these months.
Proper preparation is just as important as timing. A sealcoat applied to a well-prepared surface lasts significantly longer than one applied over an unprepared surface.
All cracks should be sealed with hot-pour rubberized sealant before the sealcoat is applied. The sealant needs time to cure and stabilize before being covered. Schedule crack sealing at least 2 weeks before your sealcoating date.
See our guide on pre-winter crack sealing for detailed information.
The surface must be thoroughly cleaned to ensure sealcoat adhesion.
Cleaning steps:
Any potholes or failed patches should be repaired with hot-mix asphalt before sealcoating. Cold-mix patches should be replaced with permanent hot-mix repairs. The sealcoat covers the entire surface uniformly, but it cannot bridge holes or unstable patches.
Define clean edges where the sealcoat should start and stop. Tape off areas that should not be coated, such as concrete walkways, building foundations, and utility covers. Protect landscaping adjacent to the pavement.
A professional sealcoating crew typically follows this process:
First 24 hours: No foot traffic. The sealcoat is soft and easily damaged.
24 to 48 hours: Light foot traffic is okay. No vehicle traffic.
48 to 72 hours: Light vehicle traffic can resume. Avoid turning the steering wheel while stationary, as this scuffs the surface.
7 to 14 days: Normal traffic can resume. The surface may still show scuff marks from sharp turns.
30 days: Full cure. The sealcoat has reached maximum hardness and durability.
Oregon's wet climate means sealcoating wears faster than in drier states. The constant moisture exposure and freeze-thaw cycling stress the coating more than in regions with shorter rainy seasons. For a complete month-by-month planning view, see our Oregon paving season calendar.
Residential driveways: Sealcoat every 2 to 3 years. Higher-traffic driveways (multiple vehicles, frequent visitors) trend toward every 2 years.
Commercial parking lots: Every 2 to 4 years depending on traffic volume. High-traffic retail and restaurant parking lots may need sealcoating every 2 years. Lower-traffic office parks may stretch to 3 to 4 years.
New asphalt: Wait 6 to 12 months after installation before the first sealcoat. New asphalt needs time to oxidize and off-gas volatile oils that prevent sealcoat adhesion.
Residential driveway (400-800 sq ft): $250 to $600 for professional sealcoating. Commercial parking lot: $0.15 to $0.30 per square foot, depending on lot size, condition, and number of coats.
Sealcoating every 2 to 3 years extends pavement life by an estimated 50 to 100 percent. For a driveway that costs $5,000 to install, extending its life from 15 years to 25 years through regular sealcoating saves the equivalent of $2,000 to $3,000 in deferred replacement costs.
For commercial properties, the ROI is even more compelling because the alternative (premature repaving) costs $4 to $8 per square foot. A 50,000 square foot parking lot that lasts 10 extra years through sealcoating avoids $200,000 to $400,000 in early replacement costs.
The best sealcoating window in Oregon is open for only about 3 months. Book your contractor early to ensure you get on the summer schedule.
Cojo Excavation and Asphalt provides professional sealcoating services for residential and commercial properties along the I-5 corridor from Portland to Eugene. We use commercial-grade coal tar emulsion sealcoat applied in two coats for maximum durability.
Check our service area for coverage in your area, or contact us at 541-409-9848 to schedule your sealcoating appointment.
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