Historical weather data, all-time temperature records, and monthly climate averages for Vashon, WA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th on Vashon splits the difference between winter and spring — the average high of 56° and low of 40° capture that classic in-between feeling. There's a coin-flip chance of rain (49%), though snow is essentially off the table. The date's range tells the whole story: a balmy 75° in 1966, a frosty 31° in 1948.
Vashon's weather has a wild side that its mild reputation doesn't always advertise. The island hit a scorching 108° on June 28, 2021 — the infamous Pacific Northwest heat dome — and plunged to exactly 0° back in January 1950. That same brutal winter delivered 20 inches of snow in a single day, a record that still stands 75 years later.
Vashon is classic western Washington: mild, wet, and green most of the year. The warmest stretch runs mid-July through mid-August, with average highs topping out around 76–77°, while early January is the coolest at just 44°. If you're rain-averse, avoid late November — the wettest week of the year averages 1.63 inches of precipitation.