weather in issaquah.
Issaquah, Washington, gets 50 inches of rain per year. The US average is 39. Snowfall is 5 inches. The average US city gets 26 inches of snow per year. The number of days with any measurable precipitation is 92. On average, there are 154 sunny days per year in Issaquah, Washington. The July high is around 75 degrees. The January low is 35. Sperling's comfort index for Issaquah is a 76 out of 100, where a higher score indicates a more comfortable year-around climate. The US average for the comfort index is 54.