Mercer Island, WA Weather Forecast
Local 7-day forecast
Mostly Cloudy
Track current conditions, temperature changes, wind, and the full daily outlook for Mercer Island, WA in one place.
Mostly cloudy, with a high near 60. North northwest wind around 2 mph.
Local Weather Overview
This forecast page for Mercer Island, WA is designed for quick trip planning, giving you a clean read on daytime highs, overnight lows, and changing conditions across the upcoming forecast window. Latest sync: Oct 18, 2026 8:38 PM PDT.
The active forecast window currently covers Oct 19 to Oct 25, 2026 for Mercer Island, WA.
Page Snapshot
- Page focus
- city weather
- Forecast window
- Oct 19 to Oct 25, 2026
- Latest sync
- Oct 18, 2026 8:38 PM PDT
- Forecast office
- SEW
- Source
- NOAA / NWS
Daily Outlook
This Week in Mercer Island
Wednesday looks like the warmest upcoming period in Mercer Island at 63 degrees F.
Friday Night is the coolest period ahead with temperatures near 42 degrees F.
The strongest winds are forecast for Tuesday at about 6 to 9 mph NNE.
Precipitation is mentioned in 7 upcoming forecast periods.
Forecast Details
- Last updated
- Oct 18, 2026 8:38 PM PDT
- Coverage
- 7 days
- Time zone
- America/Los_Angeles
- Forecast office
- SEW
- Radar station
- KATX
Weather data is provided by the National Weather Service and refreshed automatically for U.S. locations.
Open NOAA sourceExtended Forecast
Mostly cloudy, with a low around 49. North wind 2 to 6 mph.
Mostly sunny, with a high near 60. North northeast wind 6 to 9 mph.
Mostly clear, with a low around 48. North northeast wind 3 to 7 mph.
Sunny, with a high near 63.
Partly cloudy, with a low around 46.
A chance of rain showers after 5pm. Partly sunny, with a high near 60.
A chance of rain showers. Mostly cloudy, with a low around 46.
A slight chance of rain showers. Mostly sunny, with a high near 59.
A slight chance of rain showers before 5am. Mostly cloudy, with a low around 42.
A slight chance of rain showers after 11am. Partly sunny, with a high near 58.
A slight chance of rain showers. Mostly cloudy, with a low around 43.
A slight chance of rain showers before 11am. Partly sunny, with a high near 58.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
Monday
Oct 19
|
Mostly Cloudy
|
60°F |
2 mph
NNW
|
|
Monday Night
Oct 19
|
Mostly Cloudy
|
49°F |
2 to 6 mph
N
|
|
Tuesday
Oct 20
|
Mostly Sunny
|
60°F |
6 to 9 mph
NNE
|
|
Tuesday Night
Oct 20
|
Mostly Clear
|
48°F |
3 to 7 mph
NNE
|
|
Wednesday
Oct 21
|
Sunny
|
63°F |
3 mph
NE
|
|
Wednesday Night
Oct 21
|
Partly Cloudy
|
46°F |
2 mph
NE
|
|
Thursday
Oct 22
|
Partly Sunny then Chance Rain Showers
|
60°F |
3 mph
SSW
|
|
Thursday Night
Oct 22
|
Chance Rain Showers
|
46°F |
3 mph
S
|
|
Friday
Oct 23
|
Slight Chance Rain Showers
|
59°F |
3 mph
WSW
|
|
Friday Night
Oct 23
|
Slight Chance Rain Showers
|
42°F |
2 mph
NE
|
|
Saturday
Oct 24
|
Slight Chance Rain Showers
|
58°F |
5 mph
NNE
|
|
Saturday Night
Oct 24
|
Slight Chance Rain Showers
|
43°F |
5 mph
N
|
|
Sunday
Oct 25
|
Slight Chance Rain Showers then Partly Sunny
|
58°F |
6 mph
N
|
Nearby Forecasts
Explore weather pages for nearby cities and major places around Mercer Island.
