Annual mean 12°C · wettest around November · prevailing wind SW
Warmest
22.3 °C
Coldest
6.1 °C
Wettest
16%
Windiest
3.7 m/s
Prevailing
SW
3.1 m/s average
When this place is good five ratings · thirty-six ten-day sections · click a cell to read it
never good
never good
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Every reading
bars actual · line feels-like, °Cchance of rain, %wind speed, m/ssky covered, %
The average temperature in Issaquah over the whole year is 12°C. July is the hottest month, with highs of about 23°C; February is the coldest, with lows of about 4°C. The rainy (wet) season in Issaquah runs from October to April, peaking in November with a 21% chance of rain on a given day. The dry season is May to September; July is the driest month, at 3%. Winds in Issaquah are highest in April, averaging 2.9 m/s (10 km/h), and lightest in September, at 2.2 m/s (8 km/h). The prevailing wind is from the SW. The clearest skies in Issaquah come in July, when the sky is typically 36% covered; December is the cloudiest month, at 75%.
Month by month Issaquah climate by month: average temperatures year round · click a month to read it
Month
High
Low
Feels like
Chance of rain
Cloud
Wind
Being outside
Sun
Walking
January
7°C
4°C
4°C
20%
74%
2.4 m/s
0
0
27
February
7°C
4°C
3°C
17%
75%
2.7 m/s
0
0
25
March
10°C
5°C
6°C
16%
66%
2.8 m/s
3
0
45
April
13°C
7°C
9°C
13%
61%
2.9 m/s
11
0
69
May
17°C
11°C
14°C
8%
57%
2.5 m/s
41
2
88
June
20°C
13°C
17°C
7%
54%
2.6 m/s
67
7
86
July
23°C
15°C
21°C
3%
36%
2.5 m/s
90
18
74
August
23°C
15°C
21°C
4%
40%
2.4 m/s
88
23
69
September
19°C
13°C
17°C
8%
53%
2.2 m/s
77
6
86
October
14°C
9°C
11°C
15%
61%
2.3 m/s
24
0
82
November
10°C
7°C
6°C
21%
71%
2.6 m/s
3
0
48
December
7°C
5°C
3°C
20%
75%
2.5 m/s
0
0
24
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short Issaquah weather by season
Year round, Issaquah has days of about 7°C at their warmest in January, its coolest month, and 23°C in July, its warmest; the coolest hours of the day run from 4°C to 15°C through the year, and the average temperature over the year is 12°C around the clock. Rain is most likely around November and least likely around July. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
Issaquah weather in winterDecember to February
High 7°CLow 4°CRain 19%
Winter in Issaquah has typical daily highs of about 7°C and lows of about 4°C, with a 19% chance of rain on a given day.
Issaquah weather in springMarch to May
High 13°CLow 8°CRain 12%
Spring in Issaquah has typical daily highs of about 13°C and lows of about 8°C, with a 12% chance of rain on a given day.
Issaquah weather in summerJune to August
High 22°CLow 15°CRain 5%
Summer in Issaquah has typical daily highs of about 22°C and lows of about 15°C, with a 5% chance of rain on a given day.
Issaquah weather in autumnSeptember to November
High 14°CLow 10°CRain 15%
Autumn in Issaquah has typical daily highs of about 14°C and lows of about 10°C, with a 15% chance of rain on a given day.
When is the rainy season in Issaquah?
The rainy (wet) season in Issaquah runs from October to April, peaking in November with a 21% chance of rain on a given day. The dry season is May to September; July is the driest month, at 3%.
What time of year is Issaquah windiest?
Winds in Issaquah are highest in April, averaging 2.9 m/s (10 km/h), and lightest in September, at 2.2 m/s (8 km/h). The prevailing wind is from the SW.
What is the average temperature in Issaquah year round?
The average temperature in Issaquah over the whole year is 12°C. July is the hottest month, with highs of about 23°C; February is the coldest, with lows of about 4°C.