Weather in Mercer Island, WA
Mercer Island, Sunday, 9 August, 03:16
Clear. Feels like 59°. High 78°, low 57°.
Monthly outlook for Mercer Island, WA: average high 76.8°, average low 57.9°. That is 1° above the climate normal for August. Precipitation is expected on 5 days (about 1.5 inches), against a normal of 3 days and 0.8 inches. The warmest day looks like 15 August (85.9°), the coolest 10 August (52.6°).
Ten-day blocks vs climate normal
| Period | Forecast high | Normal | Difference |
|---|---|---|---|
| 9 August – 18 August | 80.1° | 76° | +2.3° |
| 19 August – 28 August | 71.2° | 73.5° | -1.3° |
| 29 August – 7 September | at normal | 71.5° | — |
August records over 66 years
Climate normals and records are computed from the nearest reference point — Bellevue (4 mi).
0
Mercer Island, Monday, 10 August
Overcast. High 80°, low 53°.
0
Mercer Island, Tuesday, 11 August
Clear. High 83°, low 56°.
0Mercer Island, Wednesday, 12 August
Clear. High 82°, low 57°.
0Mercer Island, Thursday, 13 August
Clear. High 84°, low 57°.
0Mercer Island, Friday, 14 August
Overcast. High 85°, low 59°.
0Mercer Island, Saturday, 15 August
Overcast. High 86°, low 59°.
0Mercer Island, Sunday, 16 August
Overcast. High 84°, low 58°.
0.39
Mercer Island, Monday, 17 August
Rain. High 62°, low 58°.
0
Mercer Island, Tuesday, 18 August
Partly cloudy. High 78°, low 58°.
0Mercer Island, Wednesday, 19 August
Overcast. High 77°, low 60°.
0.11Mercer Island, Thursday, 20 August
Light rain. High 80°, low 63°.
0.04Mercer Island, Friday, 21 August
Light rain. High 73°, low 61°.
0.36Mercer Island, Saturday, 22 August
Light rain. High 66°, low 60°.
0Mercer Island, Sunday, 23 August
Overcast. High 71°, low 56°.
0.6Mercer Island, Monday, 24 August
Rain. High 59°, low 55°.
0.07
Mercer Island, Tuesday, 25 August
Climate normal for this date — 60-year average.
0.05Mercer Island, Wednesday, 26 August
Climate normal for this date — 60-year average.
0.08Mercer Island, Thursday, 27 August
Climate normal for this date — 60-year average.
0.04Mercer Island, Friday, 28 August
Climate normal for this date — 60-year average.
0.11Mercer Island, Saturday, 29 August
Climate normal for this date — 60-year average.
0.07
Mercer Island, Sunday, 30 August
Climate normal for this date — 60-year average.
0.06Mercer Island, Monday, 31 August
Climate normal for this date — 60-year average.
0.08Mercer Island, Tuesday, 1 September
Climate normal for this date — 60-year average.
0.08Mercer Island, Wednesday, 2 September
Climate normal for this date — 60-year average.
0.08Mercer Island, Thursday, 3 September
Climate normal for this date — 60-year average.
0.06Mercer Island, Friday, 4 September
Climate normal for this date — 60-year average.
0.07Mercer Island, Saturday, 5 September
Climate normal for this date — 60-year average.
0.1Mercer Island, Sunday, 6 September
Climate normal for this date — 60-year average.
0.06Mercer Island, Monday, 7 September
Climate normal for this date — 60-year average.
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Mercer Island, WA are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Mercer Island, WA since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.
Sun and moon today
Weather history
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