Weather forecast for 10 daysMercer Island, WA

Weather forecast for the weekend

Saturday Oct 17, 2026

  • 61°F
  • 43°F
AM Clouds / PM Sun
AM Clouds / PM Sun
  • Precip. probability: 19%
  • Precipitation: 0"
  • Wind: 7mphNNE 31°
  • Humidity: 75%
  • UV index: 3
  • Sunrise: 7:31 am PDT
  • Sunset: 6:17 pm PDT
  • ▼
On Saturday, in Mercer Island, cloudy conditions in the morning will give way to a clearer and sunnier afternoon.
Temperatures are expected to range from a maximum of an enjoyable 60.8°F to a minimum of a brisk 42.8°F.
Today's maximum temperature is expected to reflect the standard October high of 58.6°F.
Sunrise was at 7:31 am and sunset will be at 6:17 pm; the daylight will last for 10h and 46min.

Sunday Oct 18, 2026

  • 59°F
  • 46°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 15%
  • Precipitation: 0"
  • Wind: 8mphN 2°
  • Humidity: 73%
  • UV index: 3
  • Sunrise: 7:32 am PDT
  • Sunset: 6:15 pm PDT
  • ▼
Tomorrow, on Sunday, October 18, sunny moments will alternate with patchy cloud cover.
Temperatures are expected to peak at a mild 59°F and drop to a minimum of a chilly 46.4°F.
The highest temperature for tomorrow is expected to reflect October's average of 58.6°F.
Sunrise will be at 7:32 am and sunset at 6:15 pm; tomorrow's daylight will last for 10h and 43min.

10-day overview

Daily temperatures

Warmest day: Wednesday 63°C.
Coldest period: Saturday - Monday 55°C.

Chance of precipitation

Highest chance: Friday 36%.

Long-term weather forecast

  • Saturday
  • Oct 17, 2026
  • 61°F
  • 43°F
AM Clouds / PM Sun
AM Clouds / PM Sun
  • Precip. probability: 19%
  • Precipitation: 0"
  • Wind: 7mphNNE 31°
  • Humidity: 75%
  • UV index: 3
  • Sunrise: 7:31 am PDT
  • Sunset: 6:17 pm PDT
  • ▼
  • Sunday
  • Oct 18, 2026
  • 59°F
  • 46°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 15%
  • Precipitation: 0"
  • Wind: 8mphN 2°
  • Humidity: 73%
  • UV index: 3
  • Sunrise: 7:32 am PDT
  • Sunset: 6:15 pm PDT
  • ▼
  • Monday
  • Oct 19, 2026
  • 59°F
  • 45°F
Cloudy
Cloudy
  • Precip. probability: 20%
  • Precipitation: 0"
  • Wind: 4mphWNW 292°
  • Humidity: 72%
  • UV index: 2
  • Sunrise: 7:34 am PDT
  • Sunset: 6:13 pm PDT
  • ▼
  • Tuesday
  • Oct 20, 2026
  • 61°F
  • 43°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 20%
  • Precipitation: 0"
  • Wind: 9mphN 1°
  • Humidity: 73%
  • UV index: 3
  • Sunrise: 7:35 am PDT
  • Sunset: 6:11 pm PDT
  • ▼
  • Wednesday
  • Oct 21, 2026
  • 63°F
  • 45°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 8%
  • Precipitation: 0"
  • Wind: 4mphN 353°
  • Humidity: 71%
  • UV index: 3
  • Sunrise: 7:36 am PDT
  • Sunset: 6:09 pm PDT
  • ▼
  • Thursday
  • Oct 22, 2026
  • 57°F
  • 46°F
Mostly Cloudy
Mostly Cloudy
  • Precip. probability: 24%
  • Precipitation: 0.12"
  • Wind: 6mphSW 235°
  • Humidity: 78%
  • UV index: 2
  • Sunrise: 7:38 am PDT
  • Sunset: 6:08 pm PDT
  • ▼
  • Friday
  • Oct 23, 2026
  • 57°F
  • 45°F
AM Showers
AM Showers
  • Precip. probability: 36%
  • Precipitation: 0.04"
  • Wind: 6mphSW 227°
  • Humidity: 74%
  • UV index: 2
  • Sunrise: 7:39 am PDT
  • Sunset: 6:06 pm PDT
  • ▼
  • Saturday
  • Oct 24, 2026
  • 55°F
  • 45°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 24%
  • Precipitation: 0"
  • Wind: 6mphNNE 21°
  • Humidity: 76%
  • UV index: 2
  • Sunrise: 7:41 am PDT
  • Sunset: 6:04 pm PDT
  • ▼
  • Sunday
  • Oct 25, 2026
  • 55°F
  • 45°F
Partly Cloudy
Partly Cloudy
  • Precip. probability: 24%
  • Precipitation: 0"
  • Wind: 6mphNNE 18°
  • Humidity: 72%
  • UV index: 2
  • Sunrise: 7:42 am PDT
  • Sunset: 6:02 pm PDT
  • ▼
  • Monday
  • Oct 26, 2026
  • 55°F
  • 45°F
Mostly Cloudy
Mostly Cloudy
  • Precip. probability: 24%
  • Precipitation: 0.12"
  • Wind: 5mphSW 221°
  • Humidity: 73%
  • UV index: 2
  • Sunrise: 7:44 am PDT
  • Sunset: 6:01 pm PDT
  • ▼
Over the next ten days, primarily cloud-filled and occasionally rain-filled weather is expected.
Rain is anticipated on Thursday, Friday and next Monday. The days with the most rainfall will be Thursday and next Monday, with minimal precipitation of 0.12".
In the upcoming period, the maximum temperature will range between 55.4°F and 62.6°F, while fluctuations in the night’s lowest temperature will be minimal, as the minimum temperature will fluctuate between 42.8°F and 46.4°F.
Wednesday will be the warmest day, with a maximum temperature of 62.6°F; with a maximum temperature of 55.4°F, next Saturday through next Monday will be the coldest days.
Updated: Oct 17, 2026 @ 14:56:21 UTC
Published by: Weather U.S. | About Us
Data Sources | weather.com | Weather
Weather Forecasting & Climate

Frequently asked questions

Today, a cloudy morning is expected, followed by brighter skies in the afternoon.

Today, the maximum temperature will be 60.8°F, while the minimum temperature will be 42.8°F.
Today, the maximum temperature will be in line with the average highest temperature in October. The lowest temperature will be also in line with the average low of 44.2°F.

On Saturday, in Mercer Island, sunrise was at 7:31 am and sunset will be at 6:17 pm (PDT).

In Mercer Island, the length of the day today will be 10h and 46min.

On Sunday, moments of sunshine will break through the patchy clouds.

Tomorrow, the maximum temperature will be 59°F, while the minimum temperature will be 46.4°F.
Tomorrow, the highest temperature will be in line with the average maximum temperature in October. The lowest temperature tomorrow will be also in line with the average low temperature.

On Sunday, in Mercer Island, sunrise will be at 7:32 am and sunset at 6:15 pm (PDT).

In Mercer Island, tomorrow, there will be 10h and 43min of daylight.