For optimum conditions (assuming you enjoy drier and warmer weather), Vancouver’s best months are July and August. The city typically receives plenty of rain from November through April (on average the city experiences some 150 days of rain each year). Weeks can go by with gloomy skies and rain every single day. During particularly cold and rainy years, Vancouver may not experience a day above 80F until the end of June with daytime high temperatures commonly in the 50s and low 60s even in late Spring and into early summer.
For someone used to sunny southern California weather, temperatures from October through April can be downright chilly, both day and night. However, in comparison to the rest of Canada – Vancouver’s temperatures and overall climate is fairly mild. While the city can see some snow on the ground at sea level (averages between 30 and 40cm each year), the city doesn’t experience epic snowstorms like other parts of Canada.