Mercer Island weather in September (Washington State, United States of America)
Looking to travel to Mercer Island in September? Wondering if it's the right time to visit? Browse this page for a comprehensive overview of the weather conditions for that month.
In Mercer Island, September is characterized by pleasant temperatures and moderate rainfall. September falls within the summer season. Throughout the daytime, temperatures often hover around 22°C. However, as the sun sets and evening approaches, there's a noticeable cool-down, with temperatures gently dropping to a more temperate 12°C.
Mercer Island in September usually receives moderate rainfall, averaging around 52 mm for the month. Rain is expected on roughly 10 days.
The city usually sees around 220 hours of sunlight, indicating many sunny days.
So this is a great month to visit if you prefer dry days with pleasant temperatures. June, July, August and September typically offer the most optimal weather. In contrast, January, February, March, November and December tend to have less optimal conditions.
For an in-depth look at the yearly conditions, visit our specialized Mercer Island climate page with graphs.
Mercer Island, monthly averages in September
Min Temperature
12°C
Max Temperature
22°C
Chance of Rain
33%
Precipitation
52 mm
Rainy days
10 days
Humidity
73% *
Windspeed
14 km/h *
Sunshine
220 hours *
Percentage Sunshine
59% *
Where to go in the United States of America in September
Find out more about the weather in the United States of America in September and which places have the best weather conditions in this month.
perfect weather
pleasant
tolerable
unpleasant
poor
So, what should you wear in Mercer Island in September?
For visitors traveling to Mercer Island, we recommend wearing layers. So maybe a skirt, t-shirt, shorts for during the day and jeans and a warm jacket for some days and evenings. Bring a rain jacket in case it rains during your stay. Plan on layering your clothes.What To Do
We rated the following activities from 1 (least suitable) to 10 (best) to do in September.
Interested in more climate information?
Weather and Climate provides you with all the information you need about the climate in Mercer Island.
Our site offers climate and forecast data for every country in the world. Are you going to the United States of America? On this website you can find historical weather averages for many cities in the United States of America. Not sure yet where to go? We now have a tool which recommends destinations that suit your ideal climate conditions. Find out where to go with our weather planner.
