Seattle Weather in September: What To Expect on Your Vacation

Seattle is among the most popular cities on the West Coast and Washington State. This sprawling city nestled on the Pacific Coast is the perfect hub when you want to have a city escape but experience much of what the Pacific Northwest has to offer. 

Planning your getaway to Seattle doesn’t need to be complicated. Finding the perfect time of year to visit will ensure you can do everything you want to during your visit. September is a great travel month because most places are ending their summer months and approaching comfortable fall weather.

If you’re thinking about traveling to Seattle in September, knowing all the ins and outs of the weather can help you make your decision. Here’s everything you need to know about the weather in Seattle in September.

September Weather

If you’ve never traveled to Seattle or anywhere in the Pacific Northwest, you probably have assumptions about the weather there. Most people associate Seattle with an excessive amount of rain and colder temperatures.

While it’s true that Seattle is a rainy city and the temperatures can be cooler, that doesn’t mean that you’ll get drenched every month of the year. Here’s a glimpse at the weather you can expect in Seattle in September.

Average Temperatures in September

Temperatures in Seattle during this month are lovely. They’re very comfortable during the day, and you won’t be freezing even in the evening. Well, most people won’t be freezing. You’ll probably need a jacket if you’re not used to colder weather. 

The average high temperature in September is 69°F, and the average low is 50°F. These fall temperatures are refreshing for those living with higher temperatures throughout the year. For those who live in colder environments, this will be a great break from the frigid temperatures. 

Even though the average high temperature is 69°F, towards the middle of the month, you’ll see some temperatures reaching well into the low to mid-70s. But, for planning purposes, you’ll want to prepare for temperatures in the high 60s during the day and always check the weather closer to your departure date to pack accordingly. 

Average Rainfall in September

It’s no secret that Seattle is a rainy city, but it’s only ranked 41st of the rainiest cities in the United States! On average, Seattle only sees 0.28 inches of rainfall throughout September. 

The number of days it usually rains in Seattle during this time is only six. And even if it is the six days you’re there, it won’t be raining a lot or enough to put a damper on your day. This city’s minimal rainfall and few rainy days in September make it one of the best times to visit Seattle. 

You can walk through the city without carrying an umbrella, visit the beaches, go hiking, and more without stressing about getting drenched from the rain. It doesn’t hurt to have an umbrella just in case, though. As always, check the weather before leaving to ensure you bring an umbrella if necessary.

Average Humidity in September

Not everyone cares about how humid or not a place is. If you’re curious, let’s look at the humidity you can expect when visiting Seattle in September.

The average relative humidity in Seattle is 75%. Relative humidity of 75% is one of the city’s lowest relative humidity percentages, as it usually stays in the high 70s and mid-80s. 

Average Snowfall in September

Even though Seattle is one of the northernmost states, the temperatures are chilly but not freezing. During this month, you don’t need to worry about any snow in Seattle in September. It typically only snows in Seattle for two months of the year, January and February.  

The average snowfall in September is 0 inches due to the temperate climate. While the temperatures are cooler than in other places in the country in September, snowfall won’t be something you need to worry about.

Average Cloud Coverage in September

Even though rainfall is minimal to non-existent in September, there will be cloud coverage. As September approaches, the city begins seeing much more cloud coverage than it did in August or July.

You’ll have overcast and cloudy skies for about 45% of the month. Remember, just because it’s cloudy doesn’t mean you’ll get rained on all day. The earlier in the month you go, the clearer the skies will most likely be.

Ocean Temperatures

Despite being a major city, Seattle has some beautiful little beaches that are worth checking out during your stay. While most people prefer to lounge in the sand with a good book, a meal, or simply appreciate nature, if you’re considering dipping your toes into the waters or going kayaking, knowing the average water temperatures is a good idea. 

The temperatures of the Pacific Ocean are usually reasonably chilly, especially the further north you go. Since Seattle sits in one of the northernmost parts of the United States, the temperatures are generally chilly. September sees the warmest average sea temperatures for the water around Seattle. 

The average sea temperature in Seattle during the month of September is 53°F. These aren’t precisely swimming temperatures, but you can still go kayaking with proper clothing to keep you warm.

Water Safety Considerations

Surfing isn’t as popular in Seattle as it is on other Pacific Ocean beaches, but that doesn’t mean people don’t do it here. If you’re considering surfing or swimming in the ocean during September, you need to be careful. 

Any water that’s under 70°F is considered cold water. Even if you regularly swim in waters in the 60s and find it comfortable, there are safety concerns to be aware of. Water temperatures below 60°F are considered especially dangerous because they can affect your breathing, which can cause further fatigue, and you can drown. 

The cold shock to your body can cause almost immediate breathing issues. Even if you make it out of the water to land, hypothermia is a significant concern. Overall, it’s best to avoid swimming in the water in Seattle in September, but if you’re considering it, you need proper protection. You’ll need a wetsuit that can protect you from these temperatures. 

Daylight Hours in Seattle in September

When traveling, having plenty of hours of daylight is desirable. This allows you to get into all your activities without worrying about darkness falling on you. For the most part, Seattle sees 12.5 hours of daylight throughout September. 

August is the month with the most daylight hours, so the earlier you go in the month of September, the more hours of daylight you’ll have. The later you go in the month, that average of 12.5 will more than likely be less. 

Average Hours of Sunshine in Seattle in September

Daylight and sunshine aren’t the same things. You could have a cloudy day, and it still is daylight! September brings quite a bit of sunshine to Seattle. While there is usually a good amount of cloud coverage, you can still expect around nine hours of sunshine on average throughout September.

What To Pack

Packing for a trip can be exciting but a little challenging when considering the varying weather conditions. September brings moderate temperatures, little rainfall, and no snow to Seattle, so packing should be pretty straightforward. 

Besides all the standard toiletries and other packing essentials, here are a few things you won’t want to forget when packing for your trip to Seattle: 

• Comfortable walking shoes
• A light jacket
• An umbrella (just in case)

Your packing list will vary depending on your particular style and what you’re planning on doing, but these are things you won’t want to forget when traveling to Seattle in September.

Best Things To Do in Seattle in September

There is an abundance of things to do in Seattle regardless of the time of year, especially in September. This month brings the start of all the fall festivities in the city. Here are some of the best things you can do in Seattle during your visit: 

• Enjoy immaculate city views on the top of the Space Needle
• Wander through Pike Place Market
• Grab a pumpkin spice latte at the original Starbucks
• Visit the Evergreen State Fairgrounds for rides and games
• Celebrate Oktoberfest at all the breweries and other events in town
• Visit the Sunflower Festival
• Take pictures at the Pumpkin Patch Farm

FAQs

There’s a lot to know about visiting a new place, including Seattle. If you still have questions about planning your trip to this beautiful city, these frequently asked questions should be able to provide you with some insight.

Is September a good time to visit Seattle?

September is a great time to visit Seattle! Most people would agree that the best times to visit this city are September and October. You have less rain than many other months of the year, and the temperatures are generally comfortable for all activities you want to partake in. 

What is the rainiest month in Seattle?

The rainiest month in Seattle is November. On average, the city will see over six inches of rainfall throughout the month, making it the wettest month of the year.

What is the driest month in Seattle?

If you want to visit Seattle with the least likely chance of dealing with rain daily, you should try to go in July. The city sees, on average, less than an inch of rainfall throughout the month.

How many days should I spend in Seattle on my first visit?

You can spend as little or as much time in Seattle as you want, but for first-time visitors who want to experience a little bit of everything the city offers, three to four days should be sufficient. You can do many things in less time, but three to four days is perfect if you don’t like feeling rushed. 

What is Seattle best known for?

Seattle is known for a lot of things. The most famous things Seattle is known for are Starbucks (the original one is there), Pike Place Market, the Space Needle, the tech industry, grunge music, and more.

Final Thoughts

The weather in Seattle in September is beautiful. Temperatures stay in the 50s, and high 60s throughout the month, sometimes pushing into the low 70s. You’ll be able to wander downtown without getting poured on, experience warmth from the sunshine, and enjoy all the outdoor activities you want.

With comfortable temperatures, little to no rainfall, no snow, and plenty of sunshine, September is a great time to visit Seattle. 

If you’re heading to Seattle and still need somewhere to stay, take a look at our guide exploring the best hotels in Seattle for families.