SeaTac Weather in September

September in SeaTac sees daytime temperatures around 22°C (72°F) and lows of 12°C (54°F) at night. The perfect weather makes it a good time to visit.

Rainfall in SeaTac in September

Typically around 9 days of rainfall are expected, averaging 49 mm (1.9 in) for the month. Expect a fairly normal spread of rainfall this month, with no particular pattern of very heavy or very persistent showers.

Temperature in SeaTac in September

The temperature in SeaTac in September is perfect. Daytime highs reach 22°C (72°F), with nights dropping to 12°C (54°F). The month of September belongs to the summer season. Temperatures can feel cooler in the morning and evening, so layering is often the best approach. Nights drop to around 12°C (54°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable.

Sunshine in SeaTac in September

There are approximately 220 hours of sunshine this month, resulting in mostly clear days.

Wind Speed in SeaTac in September

In September, average wind speeds reach 4 m/s (8 knots), leading to light to moderate breezes. Conditions vary from day to day, with both calm and windier periods.

Our weather planner can help you find worldwide destinations with pleasant weather during this period. June, July, August and September typically offer the best weather for SeaTac.

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• January
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For a detailed overview over the year and the best time to visit the United States of America, check out our SeaTac's climate page.

SeaTac Temperature in September

Min Temperature 12°C (54°F)  

Max Temperature 22°C (72°F)  

Chance of Rain 31%  

Precipitation 49 mm (1.9 in)  

Rainy days 9 days  

Humidity 73% *  

Windspeed 4 m/s (8 knots) *  

Sunshine 220 hours *  

Percentage Sunshine 59% *  

What to Wear in SeaTac in September

For SeaTac in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Rain is likely on several days, so bring a good rain jacket. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.

What To Do in SeaTac in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Cycling

10/10

Walking

10/10

Barbeque

9/10

Camping

10/10

Outdoor sports

10/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our SeaTac's climate page.

More climate data for SeaTac

Temperature Rainfall Sunshine Humidity Wind Speed

See the full SeaTac climate overview or explore weather in the United States of America.