Seattle Weather in August

🇺🇸 United States

25°C

High

14°C

Low

Rain Days

12h

Sunshine

65%

Humidity

North America › 🇺🇸 United States › Seattle

Updated: March 2026

Is August a Good Time to Visit Seattle?

7/10

Good

August is a good time to visit Seattle (7/10). With 12 daily sunshine hours and only 5 rain days, this month delivers genuinely reliable outdoor conditions, ranking it 3rd sunniest of the year in Seattle. Culture-focused travellers and those who prefer lighter crowds will find August a practical choice, with prices running lower than peak July without sacrificing all the good weather. September offers a similar profile at lower hotel rates if dates are flexible. The main practical note: Seattle's popular sites are busiest between 10am and 3pm regardless of season. Arriving at opening time or after 4pm makes a significant difference to the experience. Planning tips: accommodation is generally available without long lead times, and flight prices are typically lower than peak season. Flexible travellers will find the best deals by booking 2-4 weeks ahead. Mid-week arrivals consistently unlock lower hotel rates than weekend check-ins.

vs July:25°C avg high

Seattle in August rewards travelers with average highs of 25°C and overnight lows around 14°C. Expect around 5 rainy days, making it one of the drier periods in the city. With 12 daily sunshine hours on average, conditions are comfortable for sightseeing at a relaxed pace.

25°C

Avg High

14°C

Avg Low

5 days

Rain Days

12h

Sunshine

65%

Humidity

Temperature in Seattle in August

The 11°C day-night temperature range is typical for continental climates: a light jacket in the morning that you shed by midday and need again after sunset. Humidity averages 65%, which is comfortable for most visitors. On warmer days, lighter fabrics help with the mild stickiness in the afternoon. UV index averages 10 this month, classed as high to very high. SPF 30+ sunscreen, a brim hat, and sunglasses are not optional between 10am and 4pm. Winds are calm at an average 12 km/h, so wind-chill is not a factor in planning your clothing. In Fahrenheit: 77°F average high, 57°F overnight low. Data sourced from Open-Meteo ERA5 climate reanalysis (1991–2020 normals).

Temperature in August

Monthly Precipitation (mm)

What to Wear in Seattle in August

Morning14°CBefore the day warms up

Afternoon25°CPeak daytime temperature

Evening17°CAfter sunset cools down

Packing for Seattle in August means dressing for 25°C days and 14°C evenings. A light cotton tee with a casual overshirt works well at 25°C, the overshirt doubles as a layer for air-conditioned venues. Evenings drop 11°C to around 14°C, a notable shift that catches underprepared visitors off guard. Pack a dedicated evening layer. Comfortable walking trainers are the versatile choice for both outdoor sightseeing and indoor venues.

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Local tip: Layers are more practical than a single heavy garment in Seattle. The day-to-evening temperature shift rewards packing a versatile mid-layer you can add or remove as conditions change.

Events in Seattle in August

August has no major festivals or public holidays in Seattle, which is one of its practical advantages for independent travellers. Attractions run at lower capacity than during peak event periods, queues are shorter, and accommodation is easier to find without needing to book many months in advance. Local restaurants, markets, and transport operate at a relaxed pace, making this an ideal time for visitors who prefer a more authentic, unhurried experience of everyday city life rather than large crowds drawn in by a single major headline event.

What to Pack for Seattle in August

Based on 25°C average highs and 5 rainy days

Light layers for morning and evening
Breathable T-shirts and comfortable trousers
UV-protective sunglasses
SPF 30+ sunscreen
Comfortable walking shoes (a second pair lets the first air out overnight)
Universal travel adapter
Small day pack for city exploration
Reusable water bottle

Best Activities in Seattle in August

Explore outdoor markets and street food stallsMid-morning (10am-12pm)At 25°C, the temperature is ideal for extended walking without overheating
Guided walking tour of the historic centreMorning or late afternoonComfortable temperatures allow several hours on foot without fatigue
Visit rooftop viewpoints and observation decksGolden hour (1 hour before sunset)Warm clear evenings provide exceptional visibility for panoramic photography
Day trip to the surrounding countryside or coastFull day (depart by 8am)August is reliably dry enough for rural day trips without weather risk
Afternoon in a world-class museum or galleryAfternoon (2-5pm)Pairs well with outdoor morning activities and provides a mid-day rest from sightseeing
Coffee-house or traditional cafe culture experienceMid-morning or post-lunchA cultural ritual in this region that rewards slow appreciation regardless of weather
Evening live music, theatre, or opera performanceEvening shows typically at 7-9pmConsistent evening temperatures make getting to and from evening venues comfortable
Visit the main botanical garden or city park at seasonal peakYear-round; best light in morningAugust brings distinct seasonal changes to public green spaces worth exploring
Try the seasonal farmer's market for local produce and street foodSaturday morning markets typically 8am-1pmAugust seasonal produce is at peak availability, offering dishes not found at other times of year

Why is Seattle warm in August?

August in Seattle reflects a mid-latitude climate pattern, with temperatures averaging 25°C by day and 14°C overnight. The city sits at 48 degrees north latitude, where the balance between solar radiation and heat loss drives conditions that are neither extreme nor static. The warm temperatures reflect a stable high-pressure pattern typical of the season, which suppresses cloud formation and concentrates solar energy at the surface. Day-to-night temperature variation of 11°C is moderate and manageable with a single mid-layer. Climate data: Open-Meteo ERA5 (1991–2020).

Sunshine Hours

The average number of hours per day with direct sunlight. Calculated from satellite measurements. Days with more than 7 hours of sunshine are ideal for outdoor activities. Under 3 hours means overcast conditions dominate.

UV Index

A scale from 0-11+ measuring ultraviolet radiation intensity. UV 0-2: Minimal risk. UV 3-5: Moderate -- wear sunscreen. UV 6-7: High -- hat and SPF 30+ essential. UV 8-10: Very High -- limit midday exposure. UV 11+: Extreme -- seek shade between 10am-4pm.

Rain Days

A rain day is counted when precipitation exceeds 0.1mm. This threshold captures even light drizzle. Unlike total rainfall in mm, rain days tells you how often you might need an umbrella, which is useful for planning outdoor activities.

Humidity

Relative humidity as a percentage. Below 40%: Dry -- skin and throat may feel parched. 40-60%: Comfortable -- ideal for most people. 60-80%: Sticky -- light, breathable fabrics recommended. Above 80%: Muggy -- heat feels more intense; quick-dry clothing is essential.

Frequently Asked Questions: Seattle in August

In August, Seattle experiences average highs of 25°C (77°F) and lows of 14°C (57°F). Expect around 5 rainy days and 12 hours of sunshine per day, with humidity averaging 65%. The 11°C gap between daytime and overnight temperatures is worth planning around: light layers work for most visitors during the day, but an overshirt or cardigan handles the cooler evenings. UV index averages 10, so sun protection is advisable on clear days.

Seattle typically sees 5 rainy days in August, with total precipitation of around 34mm. This makes August one of the drier months of the year, and a reliable window for outdoor sightseeing and day trips. Rain showers tend to be brief when they do occur. For context, the driest month in Seattle typically sees 4-6 fewer rain days than August.

Pack light layers, a light jacket for evenings, comfortable walking shoes, and sunscreen for Seattle in August. Daytime temperatures of 25°C are pleasant, but the evening drop to 14°C means a jacket is essential if you plan to be out after dark. Rain is infrequent with only 5 wet days, so a light rain layer is optional. Comfortable walking shoes are a priority given the amount of ground most visitors cover.

Yes, August is an excellent time to visit Seattle. With 12 daily sunshine hours and only 5 rainy days, conditions are ideal for sightseeing and outdoor activities. Temperatures averaging 25°C during the day are comfortable for long walks and outdoor dining. This is peak travel season, so booking accommodation in advance and arriving at popular attractions early in the morning helps avoid the busiest periods.

The average high temperature in Seattle in August is 25°C (77°F), and the average low is 14°C (57°F). The mean daily temperature is approximately 20°C (67°F). The day-to-night range of 11°C is moderate, meaning a single light jacket covers most situations. These are 30-year climate normals based on the 1991 to 2020 reference period; individual years will vary, particularly in transitional months like spring and autumn.

The best month to visit Seattle is generally July. July offers the most sunshine at 13 hours per day and only 6 rainy days. Average temperatures reach 25°C, making it comfortable for sightseeing, outdoor dining, and exploring the city. If your travel dates are flexible, planning your trip around July gives you the best chance of dry, bright weather.

August is shoulder or low season in Seattle, meaning fewer tourists and generally lower prices than peak months. With 12 sunshine hours and 5 rainy days, the weather is less of a draw for mass tourism. This is an advantage for travellers who prefer a quieter, more relaxed experience with shorter queues and easier accommodation availability.

In August, Seattle suits a range of activities thanks to mild temperatures around 25°C. With few rainy days, outdoor activities are highly recommended. Top options include exploring historic neighbourhoods, visiting museums and galleries, local food markets, and day trips to surrounding areas. With 12 hours of sunshine, parks and waterfront walks are particularly enjoyable.

August ranks 3rd sunniest of the year in Seattle, with an average 12 daily sunshine hours. The driest months are August, July, and September. July is the hottest month (25°C avg high); December is the coolest (7°C). From here, temperatures fall 4°C into September. Compared to last month (July: 25°C high, 6 rain days), August is similarly warm and drier. August is among the top three sunniest months to visit Seattle.

Year-Round Climate

Month	High	Low	Rain Days	Sun	Details
January	8°C	2°C	18	4h	View
February	9°C	2°C	14	6h	View
March	11°C	3°C	18	8h	View
April	14°C	5°C	16	10h	View
May	18°C	8°C	13	11h	View
June	21°C	11°C	10	12h	View
July	25°C	14°C	6	13h	View
August	25°C	14°C	5	12h	View
September	21°C	12°C	8	10h	View
October	15°C	8°C	15	7h	View
November	10°C	4°C	18	5h	View
December	7°C	2°C	18	4h	View

Other Months in Seattle

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Plan Your Trip to Seattle

Best Time to Visit Seattle Seattle vs Vancouver in August

Data Sources for Seattle

Seattle on Wikipedia Open-Meteo Climate API NOAA National Centers UK Met Office WMO GeoNames

Climate normals represent 30-year averages (1991-2020). Individual years may vary.