September in Kirkland averages a daily high of 21.8°C with nights around 11.9°C. Expect roughly 9.2 wet days totalling 49.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Kirkland is July–August.
Based on SEATTLE SAND POINT WEATHER FORECAST OFFICE, WA US (3.5km), 1995–2024. 29 years of September data.