Issaquah in Summer
In summer (June, July and August), Issaquah sees average daytime highs around 72°F and overnight lows near 53°F, with 6.1 in of rain over about 24 wet days across the season. It is the warmest season of the year and the driest season of the year.
Over the season highs climb from about 65°F in early June to 72°F by late August. The sky is clear or mostly clear about 37% of the time across summer, and the air most often feels dry.
Summer is Issaquah's best season of the year to visit on our travel score. For the whole year in context, see Issaquah's year-round climate.
- Avg daytime high
- 72°F
- warmest season of the year
- Avg overnight low
- 53°F
- Rainfall
- 6.1 in
- 24 wet days
- Avg wind
- 4 mph
- Travel score
- 7.2
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Issaquah in Summer
Over the season highs climb from about 65°F in early June to 72°F by late August.
A typical summer day in Issaquah reaches about 72°F and drops to 53°F overnight. The warmest of the three months is August, the coolest June.
How summer really feels in Issaquah
Once humidity and wind are folded in, summer brings about 0 days that feel above 90°F and 0 that feel at or below 32°F.
summer sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Issaquah weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 45° / 35° | 8.3 | 18.7 | 3.6 | 8.7 | 0.8 |
| Feb | 48° / 36° | 5.8 | 15.5 | 2.6 | 9.9 | 1.5 |
| Mar | 52° / 37° | 6.5 | 18.7 | 1.8 | 11.6 | 2.2 |
| Apr | 57° / 41° | 5.4 | 16.5 | 0.2 | 13.3 | 3.4 |
| May | 63° / 46° | 3.8 | 12.8 | 0 | 14.9 | 5.1 |
| Jun | 67° / 50° | 3.2 | 11.4 | 0 | 15.7 | 5.9 |
| Jul | 74° / 54° | 1.3 | 6.5 | 0 | 15.4 | 7.7 |
| Aug | 74° / 54° | 1.6 | 5.7 | 0 | 14.1 | 7.9 |
| Sep | 68° / 49° | 3.4 | 9 | 0 | 12.4 | 6.6 |
| Oct | 58° / 43° | 6.6 | 15.1 | 0 | 10.6 | 3.9 |
| Nov | 49° / 38° | 9.0 | 18.7 | 1 | 9.1 | 1.6 |
| Dec | 44° / 35° | 8.1 | 18.4 | 3.4 | 8.3 | 0.6 |
Cloud cover in Summer
The sky is clear or mostly clear about 37% of the time across summer.
Chance of precipitation in Summer
Issaquah gets around 6.1 in of rain over 24 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 4 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 15 h 30 min in early June to 13 h 18 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 5.7 kWh/m².
Hazard calendar for Issaquah
None of Issaquah's seasonal hazards peak in summer. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
Issaquah's rainy season runs October–April, when most of the year's rain falls.
Is summer a good time to visit Issaquah?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is one of the better times to visit Issaquah for general sightseeing.
What to pack for Issaquah in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Issaquah sees daytime highs around 72°F and nights near 53°F. Pack sun protection. Worth having: light clothes and rain gear. About 24 days see rain.
UV index in Issaquah in Summer
Clear-sky midday UV across summer averages around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Issaquah peaks around July 17 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 17 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 1 | 4 | 5 | 7 | 6 | 8 | 6 | 4 | 3 | 1 | 1 |
| Level | Low | Low | Moderate | Moderate | High | High | Very high | High | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 1 | Low |
| Mar | 4 | Moderate |
| Apr | 5 | Moderate |
| May | 7 | High |
| Jun | 6 | High |
| Jul | 8 | Very high |
| Aug | 6 | High |
| Sep | 4 | Moderate |
| Oct | 3 | Moderate |
| Nov | 1 | Low |
| Dec | 1 | Low |
Air quality in Issaquah in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer falls, not just the annual average.
Air quality in Issaquah is worst in September — around 22 µg/m³ PM2.5 (moderate), about 3.4× the cleanest month (December, 7 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 8 | 9 | 12 | 12 | 11 | 10 | 10 | 18 | 22 | 12 | 8 | 7 |
| Level | Good | Good | Moderate | Good | Good | Good | Good | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 8 | Good |
| Feb | 9 | Good |
| Mar | 12 | Moderate |
| Apr | 12 | Good |
| May | 11 | Good |
| Jun | 10 | Good |
| Jul | 10 | Good |
| Aug | 18 | Moderate |
| Sep | 22 | Moderate |
| Oct | 12 | Good |
| Nov | 8 | Good |
| Dec | 7 | Good |
Where is Issaquah?
Issaquah sits at 47.5°N, 122.0°W, 108 ft above sea level, in United States. The nearest listed city is West Lake Sammamish, 4.3 mi away.
Topography around Issaquah
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Issaquah.
Within 2 miles, the terrain around Issaquah has large variations in elevation — a maximum elevation change of 1,998 ft around an average of 512 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,002 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 14,413 ft.
The land around Issaquah is covered by trees (78%) within 2 miles, trees (77%) within 10 miles, and trees (76%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Issaquah (47.5301°, -122.0326°, elevation 108 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.