Boasting about the weather is almost a birthright for residents of Victoria, which often ranks among the .
With a frequently hovering over B.C.'s capital while nearby communities remain under cloudy skies, this isn鈥檛 just a stroke of repetitive luck. In fact, Victoria鈥檚 enviable weather can be attributed to a simple meteorological phenomenon 鈥� a rain shadow.
Rain shadows are regions that receive significantly less rainfall due to their location, shielded by nearby mountain ranges, explained Armel Castellan, a meteorologist with Environment Canada.
A glance at a map of B.C.'s South Coast quickly reveals how this pattern takes place.
Tucked behind Washington's Olympic Peninsula, Victoria lies behind a massive mountain range to the south, which blocks moisture-laden clouds coming from the Pacific.
鈥淎s that mass of very moist air鈥� hits elevated terrain, it starts to cool because it's forced to rise up in elevation,鈥� said Castellan.
While the clouds rise, droplets start to form and gradually get bigger until they eventually fall as rain on the windward side of the mountain. Once depleted of moisture, the now-dry clouds move over to the leeward side.
鈥淣ow you've got an air mass that is descending back down to sea level and it is drying and warming at the same time,鈥� said Castellan. 鈥淎s a result, the propensity to rain is diminished greatly.鈥�
Spanning over 1,000 square kilometres, with Victoria, the San Juan Islands, Port Angeles and Port Townsend, Wash., marking its edges, the rain shadow's centre likely lies offshore in the Salish Sea, Castellan explained.
This area, easily identifiable via satellite imagery, explains Victoria鈥檚 unique meteorological patterns.
鈥淥ur weather ends up being extremely different than it would be over the western Washington coastline or the western side of Vancouver Island,鈥� said Castellan.
Rain data over the years have consistently supported the meteorologist鈥檚 claims.
Victoria, on average, receives . Sooke, 40 km east of the capital, gets 1,238 mm, while Port Renfrew receives more than double that at 2,732 mm. Nearby Vancouver averages 1,593 mm.
Castellan noted the shadow鈥檚 effect is more pronounced over the year鈥檚 wettest months, from mid-October to March. However, a rain shadow doesn鈥檛 mean an absence of precipitation.
鈥淰ictoria can get some good rains here and there, of course, [but] at the end of the year, you're pretty much guaranteed to have the least amount of rain of any coastal community on the Island.鈥�
That said, Castellan mentioned that the eastern part of Vancouver Island could also be considered somewhat in a shadow as it lies on the leeward side of several mountain ranges including Beaufort, Seymour and Pierce.
鈥淭he east side of Vancouver Island is, in a way, a partial rain shadow because if you look at what falls in Ucluelet or Tofino, it's quite a bit more than what you'll see in Campbell River, Comox or Nanaimo,鈥� said Castellan.
While several regions in B.C. and Canada experience rain shadows, Victoria鈥檚 stands out for its temperate and wet climate, particularly when compared to areas like the Okanagan 鈥� one of the country鈥檚 driest regions 鈥� which lies in the shade of the Cascade Range.
Castellan explained that, in a way, these meteorological phenomena are similar to a microclimate, influencing the fauna and flora in their shade by shaping the region's predominant weather patterns.
Greater Victoria is home to the largest remnants of one of 鈥� the Garry oak meadows. This rare habitat supports a rich diversity of life, including unique plants, mammals, reptiles, birds, and countless other insects.
Although rain shadow climates are generally drier and warmer, Castellan noted that this phenomenon does not necessarily equate to a tropical paradise.
鈥淚t would be a misconception to think that the rain shadow creates a spot where you can suddenly grow bananas.鈥�
