Mill Bay has a temperate climate that is usually classified as Marine west coast (Cfb), with mild, damp winters and relatively dry and mild summers. It is sometimes classified as a Mediterranean climate (Csb). In the summer, daily temperatures can rise above 30°C while in the winter freezing overnight temperatures are rare. Nearly two thirds of the annual precipitation falls during the four wettest months, November to February with snow being a rare treat.
Due to its mild climate, Victoria and its surrounding area (southeastern Vancouver Island, Gulf Islands, and parts of the Lower Mainlandand Sunshine Coast) is home to many rare, native plants found nowhere else in Canada, including Quercus garryana (Garry oak), Arctostaphylos columbiana (Hairy manzanita), and Canada’s only broad leaf evergreen tree, Arbutus menziesii (Pacific madrone). Many of these species exist here at the northern end of their range, and are found as far south as Central and Southern California, and even parts of Mexico.