Current Conditions

Mercer Island, Washington

62°F17°C
Partly Cloudy

Wind

ESE 3 mph5 km/h

Humidity

71%

Cloud Cover

75%

As of Tuesday, September 22, 2026 at 7:37 PM PDT

Today's Outlook

Night

Mostly cloudy, with a low around 53°F12°C. Light wind from the ESE around 5 mph8 km/h.

7-Day Forecast

DayConditionHigh (°F)Low (°F)Precip (mm)Cloud Cover (%)Wind (mph)
Partly CloudyHigh 66°F19°CLow 53°F12°CPrecip 0.01 in0.2 mm9%Cloud 80%Wind S 5 mph8 km/hWednesday: Overcast and mild, with a high of 66°F19°C and morning low of 55°F13°C. Light wind from the SSW around 5 mph8 km/h. Dry air. Wednesday Night: Mostly cloudy, with a low around 53°F12°C. Light wind from the ESE around 5 mph8 km/h.
RainHigh 60°F15°CLow 51°F11°CPrecip 0.2 in5 mm98%Cloud 98%Wind N 4 mph7 km/hThursday: Overcast and mild, with a high of 60°F15°C and morning low of 52°F11°C. Light wind from the NNW around 5 mph7 km/h. 46% chance of light rain in the afternoon. Dry air. Thursday Night: Overcast, with a low around 51°F11°C. Light wind from the NNE around 4 mph6 km/h. 98% chance of rain in the evening.
RainHigh 59°F15°CLow 52°F11°CPrecip 0.64 in16.2 mm97%Cloud 74%Wind SSW 7 mph11 km/hFriday: Overcast and mild, with a high of 59°F15°C and morning low of 54°F12°C. Breezy from the SSW at 8 to 9 mph14 to 15 km/h. 97% chance of rain throughout the day. Friday Night: Mostly cloudy, with a low around 52°F11°C. Light wind from the S around 5 mph9 km/h. 94% chance of showers throughout the night.
DrizzleHigh 61°F16°CLow 48°F9°CPrecip 0.01 in0.3 mm17%Cloud 64%Wind NNE 5 mph8 km/hSaturday: Mostly cloudy and mild, with a high of 61°F16°C and morning low of 49°F9°C. Light wind from the N around 5 mph8 km/h. Dry air. Saturday Night: Mostly cloudy, with a low around 48°F9°C. Light wind from the E around 5 mph8 km/h. 17% chance of drizzle overnight.
DrizzleHigh 63°F17°CLow 48°F9°CPrecip 0.02 in0.6 mm12%Cloud 50%Wind N 4 mph7 km/hSunday: Partly cloudy and mild, with a high of 63°F17°C and morning low of 51°F10°C. Light wind from the NNW around 5 mph8 km/h. 12% chance of drizzle in the afternoon. Dry air. Sunday Night: Mostly cloudy, with a low around 48°F9°C. Light wind from the NE around 4 mph6 km/h.
Light RainHigh 63°F17°CLow 49°F10°CPrecip 0.09 in2.4 mm30%Cloud 81%Wind S 5 mph8 km/hMonday: Overcast and mild, with a high of 63°F17°C and morning low of 50°F10°C. Light wind from the S around 5 mph8 km/h. 28% chance of drizzle throughout the day. Dry air. Monday Night: Mostly cloudy, with a low around 49°F10°C. Light wind from the SSE around 5 mph8 km/h. 30% chance of light rain throughout the night.
Light RainHigh 63°F17°CLow 54°F12°CPrecip 0.24 in6.1 mm43%Cloud 80%Wind S 6 mph10 km/hTuesday: Overcast and mild, with a high of 63°F17°C and morning low of 55°F13°C. Breezy from the SSW at 6 to 7 mph10 to 11 km/h. 43% chance of light rain throughout the day. Tuesday Night: Mostly cloudy, with a low around 54°F12°C. Light wind from the S around 6 mph10 km/h. 37% chance of light rain throughout the night.

15-Day Forecast

Day High Low Precip Cloud Cover Condition Wind
WednesdaySep 2366°F19°C53°F12°C0.01 in0.2 mm· 9%80%Partly CloudyS 5 mph8 km/h
ThursdaySep 2460°F15°C51°F11°C0.2 in5 mm· 98%98%RainN 4 mph7 km/h
FridaySep 2559°F15°C52°F11°C0.64 in16.2 mm· 97%74%RainSSW 7 mph11 km/h
SaturdaySep 2661°F16°C48°F9°C0.01 in0.3 mm· 17%64%DrizzleNNE 5 mph8 km/h
SundaySep 2763°F17°C48°F9°C0.02 in0.6 mm· 12%50%DrizzleN 4 mph7 km/h
MondaySep 2863°F17°C49°F10°C0.09 in2.4 mm· 30%81%Light RainS 5 mph8 km/h
TuesdaySep 2963°F17°C54°F12°C0.24 in6.1 mm· 43%80%Light RainS 6 mph10 km/h
WednesdaySep 3063°F17°C54°F12°C0.17 in4.4 mm· 42%72%Light RainS 6 mph9 km/h
ThursdayOct 162°F16°C52°F11°C0.19 in4.7 mm· 43%68%ShowersS 6 mph9 km/h
FridayOct 262°F17°C50°F10°C0.11 in2.7 mm· 27%59%ShowersSSE 5 mph8 km/h
SaturdayOct 364°F18°C49°F10°C0.07 in1.8 mm· 16%55%DrizzleENE 5 mph8 km/h
SundayOct 465°F18°C51°F11°C0.08 in2.1 mm· 18%59%DrizzleSSE 5 mph8 km/h
MondayOct 566°F19°C52°F11°C0.09 in2.4 mm· 23%53%DrizzleS 6 mph9 km/h
TuesdayOct 666°F19°C53°F11°C0.11 in2.9 mm· 21%51%DrizzleSSE 5 mph9 km/h
WednesdayOct 766°F19°C53°F12°C0.09 in2.3 mm· 23%57%DrizzleS 5 mph8 km/h

Nearby Cities

About This Forecast

This forecast is powered by WeatherMesh, the world's most advanced and accurate weather model powered by AI. WeatherMesh is built on proprietary data from WindBorne's Global Sounding Balloon constellation — the world's largest fleet of autonomous, long-duration weather balloons — collecting observations across 100% of Earth, including over oceans and remote regions where no other data exists.

WeatherMesh consistently outperforms legacy models in independent benchmarks. View Benchmarks →

Access WeatherMesh forecasts programmatically via our API. API Documentation →

How to Access Weather Forecasts

PatternExampleDescription
/weather/{country}/{city}//weather/united-states/san-francisco/City forecast (canonical URL)
/weather/{city}//weather/tokyo/Shorthand — redirects to most populous match
/weather/{country}/{region}/{city}//weather/united-states/california/san-francisco/With region — redirects to canonical
/weather/nearby?lat={lat}&lon={lon}/weather/nearby?lat=48.1&lon=11.5Find nearest city by coordinates
/weather/{country}//weather/germany/Country index — all cities by region

Country and city names use lowercase slugs with hyphens (e.g. united-states, san-francisco). Arbitrary city names are supported — if not in our database, we geocode the name and serve the forecast for that location.

For programmatic access, use theWindBorne Forecast APIwhich returns structured JSON for any coordinates worldwide.

Coordinates: 47.5707°N, 122.2221°W·Elevation: 102m·Timezone: America/Los_Angeles·Population: 25,042