Issaquah Weather in September

With daytime temperatures of 21°C (70°F) and nighttime lows of 11°C (52°F), September in Issaquah brings pleasant temperatures during the day. Do keep in mind that quite a bit of rainfall is typical. Around 82 mm (3.2 in) falls on average.

Rainfall in Issaquah in September

Historically, approximately 12 days this month are expected to have rain, averaging 82 mm (3.2 in). Expect a fairly normal spread of rainfall this month, with no particular pattern of very heavy or very persistent showers.

Temperature in Issaquah in September

September in Issaquah is generally perfect, with days reaching 21°C (70°F) and nights settling around 11°C (52°F). September is in the summer season. Temperatures can feel cooler in the morning and evening, so layering is often the best approach. With lows of 11°C (52°F), nights are cool. If you're out after dark, an extra layer will keep you comfortable. The cooler air at night is also great for getting a good rest.

Sunshine in Issaquah in September

Expect sunny days throughout the month, with an estimated 220 hours of sunshine. This makes it a pleasant time to visit Issaquah.

Wind Speed in Issaquah 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.

If you're a fan of comfortable temperatures and drier conditions, September is a great time to visit.

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Check the conditions for any month of the year.

• January
• February
• March
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• May
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• August

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• October
• November
• December

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

Issaquah Temperature in September

Min Temperature 11°C (52°F)  

Max Temperature 21°C (70°F)  

Chance of Rain 40%  

Precipitation 82 mm (3.2 in)  

Rainy days 12 days  

Humidity 73% *  

Windspeed 4 m/s (8 knots) *  

Sunshine 220 hours *  

Percentage Sunshine 59% *  

* Data from: Seattle, the United States of America (21 KM, 13 Miles).

What to Wear in Issaquah in September

Pleasant temperatures in September mean you can pack light but flexibel pieces. Think cotton t-shirts, comfortable walking shorts, and one warmer layer for evenings. A light sweater or denim jacket works well. Prepare for significant rainfall with proper waterproof clothing and shoes. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.

What To Do in Issaquah in September

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

Cycling

9/10

Walking

9/10

Barbeque

8/10

Camping

8/10

Outdoor sports

9/10

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 Issaquah's climate page.

More climate data for Issaquah

Temperature Rainfall Sunshine Humidity Wind Speed

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