The best times to visit South Lake Union for ideal weather are
May 7th to October 21st
based on average temperature and humidity from NOAA (the National Oceanic and Atmospheric Administration). Read below for more weather and travel details.
South Lake Union Travel Guide
Other South Lake Union Travel Info
Weather in South Lake Union
Average temperatures in South Lake Union vary greatly. Considering humidity, temperatures feel cold for about half of the year and otherwise nice with a fair chance of precipitation about half of the year. The area is less temperate than some — in the 37th percentile for pleasant weather — compared to tourist destinations worldwide. Weeks with ideal weather are listed above. If you’re looking for the very warmest time to visit South Lake Union, the hottest months are August, July, and then September. See average monthly temperatures below. The warmest time of year is generally mid August where highs are regularly around 81°F (27.2°C) with temperatures rarely dropping below 60°F (15.6°C) at night.
South Lake Union Temperatures (Fahrenheit)
South Lake Union Temperatures (Celsius)
The way we experience weather isn’t all about temperature. Higher temperatures affect us much more at higher humidity, and colder temperatures feel piercing with high winds. Our perceived temperatures factor in humidity and wind chill to better represent how hot or cold the day feels to a person.
South Lake Union Perceived Temperature (F)
South Lake Union Perceived Temperature (C)
Average South Lake Union Temperatures by Month
Daily highs (averaged for the month) usually give the best indication of the weather. A significantly lower mean and low generally just means it gets colder at night.
|Month||Avg. High (°F)||Avg. Mean (°F)||Avg. Low (°F)|
|Month||Avg. High (°C)||Avg. Mean (°C)||Avg. Low (°C)|
Precipitation (Rain or Snow)
If dry weather is what you’re after, the months with the lowest chance of significant precipitation in South Lake Union are July, August, and then June. Note that we define “significant precipitation” as .1 inches or more in this section. The lowest chance of rain or snow occurs around early to mid July. For example, on the week of July 9th there are no days of precipitation on average. By contrast, it’s most likely to rain or snow in mid December with an average of 4 days of significant precipitation the week of December 17th.
When can you find snow in South Lake Union? Weather stations report no annual snow. Please note that a value of 0 for snow in the graph below may either mean there was no snow, or that snow is unreported.
Chance of Precipitation
The graph below shows the % chance of rainy and snowy days in South Lake Union.
Snow on the Ground
The graph below shows the average snow on the ground in South Lake Union (in).
Average Rain and Snow by Month
|Month||Daily Chance of Rain||Average Snow Depth (in)||Total Precipitation (in)|
|Month||Daily Chance of Rain||Average Snow Depth (cm)||Total Precipitation (cm)|
Humidity and Wind
South Lake Union has some very humid months, with other comfortably humid months. The least humid month is July (50.1% relative humidity), and the most humid month is January (72.7%).
Wind in South Lake Union is usually calm. The windiest month is March, followed by April and December. March’s average wind speed of around 5.3 knots (6.1 MPH or 9.9 KPH) is considered “a light breeze.” Maximum sustained winds (the highest speed for the day lasting more than a few moments) are at their highest in early to mid March where average top sustained speeds reach 11.8 knots, which is considered a moderate breeze.
Relative Humidity (%)
The graph below shows the average % humidity by month in South Lake Union.
The graph below shows wind speed (max and average) in knots.
Average Wind Speeds
Show Wind Speeds
All wind speeds are in knots. 1 knot = 1.15 MPH or 1.85 KPH.
|Month||Avg. Wind||Avg. Wind Feel||Sustained High Wind||High Wind Feel|
|Jan||4.5||Light breeze||10.1||Gentle breeze|
|Feb||4.6||Light breeze||10.2||Gentle breeze|
|Mar||5.3||Light breeze||11.1||Gentle breeze|
|Apr||4.9||Light breeze||10.2||Gentle breeze|
|May||4.3||Light breeze||9.1||Gentle breeze|
|Jun||4.3||Light breeze||9.1||Gentle breeze|
|Jul||3.9||Barely noticeable||8.6||Gentle breeze|
|Aug||3.7||Barely noticeable||8.5||Gentle breeze|
|Sep||3.7||Barely noticeable||8.5||Gentle breeze|
|Oct||3.9||Barely noticeable||9.2||Gentle breeze|
|Nov||4.5||Light breeze||10.4||Gentle breeze|
|Dec||4.7||Light breeze||10.3||Gentle breeze|
Show Relative Humidity by Month
|Month||Avg. Relative Humidity|
Is it Safe to Travel to South Lake Union?
Our best data indicates this area is generally safe. As of Oct 07, 2019 there are no travel advisories or warnings for the United States; exercise normal security precautions. Check this page for any recent changes or regions to avoid: Travel Advice and Advisories. This advisory was last updated on Sep 23, 2019.
The Busiest and Least Crowded Months
The busiest month for tourism in South Lake Union, WA, US is July, followed by June and August. Prices for hotels and flights will be most expensive during these months, though you can save if you purchase well in advance. Tourists are unlikely to visit South Lake Union in November. Those willing to visit at these times will likely find it the least expensive month.
Estimated Tourism by Month
Most Popular Months to Visit
Overall South Lake Union Travel Experience by Season
Spring (March through May)
Humidity and temperatures combine to make this season feel moderately cold. Highs range from 70.3°F (21.3°C) and 52.2°F (11.2°C) with warmer temperatures in the later months. Rain is somewhat common with 6 to 11 days of significant precipitation per month. Spring is the second busiest for tourism, which makes it a good time for those looking for things to do.
Summer (June through August)
The middle-year months have very comfortable weather with high temperatures that are comfortable. These months see the least precipitation with 1 to 4 days of precipitation per month. June – August is the busiest season for tourism in South Lake Union, so lodging and other accommodations may cost more than usual.
Fall (September through November)
Fall daily highs range from 75.5°F (24.2°C) and 49.9°F (9.9°C), which will feel chilly given the humidity and wind. It rains or snows a significant amount: 4 to 12 days per month. Tourism is the slowest during these months due to the weather, so hotels may be affordably priced.
Winter (December through February)
Weather is too cold this time of year in South Lake Union to be enjoyable for warm weather travelers. The average high during this season is between 53.3°F (11.8°C) and 46.5°F (8.1°C). On average, it rains or snows a great amount: 8 to 12 times per month. These times of year are fairly slow with tourists.