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).
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 weather are 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.