Sammamish’s climate is dominated by maritime patterns that define the overall climate of the Puget Lowlands. These patterns include mild, wet fall to spring months, and cool dry summer months. Annual precipitation in the Puget Lowlands typically ranges from 32 to 37 inches, the vast majority of which is distributed between October and May. January temperatures typically range from lows around 30º F to highs around 43º F. July temperatures typically range from lows around 50º F to highs around 75º F (National Climatic Data Center [NCDC] Summary for Washington State, undated).
Precipitation typically occurs as low-intensity, long-duration storms (NCDC, undated). Precipitation as snow is relatively rare and short-lived in the lowlands. However, hydrologic systems in the Pacific Northwest are especially sensitive to warm rain-on-snow events, when significant volumes of water can be released into the system at one time.
For free historic information for a specific day see: almanac.com
For detailed weather characteristics and charts see: usa.com