Does Victoria have a Mediterranean Climate?

You may have seen Victoria described as having a Mediterranean or perhaps a sub-Mediterranean climate.  Is this just local boosterism?  People are sometimes skeptical about these claims of a Mediterranean climate.  After all, while we have great weather in Victoria, it’s not exactly southern California or the Greek Islands.  Despite the skepticism, there is in fact truth to these claims. 

The Koppen classification system, developed by Russian German climatologist Wladimir Koppen in the late 19^th century,  is one of the most widely used climate classification systems in the world.  Under the Koppen system, the world’s climates are classified into five main groups: A – Tropical, B – Dry, C – Temperate, D – Continental, and E – Polar.  Victoria falls in the the Temperate group, which is further classified based on the annual precipitation pattern, indicated by the second letter in the classification: s for dry summer, w for dry winter, and f for precipitation throughout the year.   So Cf would include Oceanic climates, like London, England, while Cs climates are termed Mediterranean.  To meet the criteria for a Cs climate, summer months must have less than one third the precipitation as the wettest winter month, and summer months must have less than 30 mm of precipitation.  Victoria easily meets these criteria, with July rainfall of just 13 mm – less than one tenth of our wettest month in December.  Mediterranean climates are further classified as Csa or Csb, depending on whether summers are hot (mean monthly temperature above 22 C) or warm (mean monthly temperature below 22 C).  Based on all these criteria, Victoria’s climate is classed as Csb, or warm summer Mediterranean.  Other locations with a Csb climate include San Francisco, Cape Town, and Porto, Portugal. 

The charts below show the monthly precipitation in Victoria, San Francisco, and London, England.  All three cities have roughly similar total annual precipitation - about 600 mm.  However, while precipitation in London is evenly distributed throughout the year, Victoria and San Francisco have the distinctive Mediterranean pattern of winter rainy season and summer drought   While Victoria's summer drought period is not quite so intense as San Francisco's, the overall pattern is still the same.

Further evidence of our Mediterranean climate can be seen in Victoria’s native vegetation, which tends to be a strong expression of the local climate.   While the vegetation of northern and western Vancouver Island can be classified as temperate rainforest, the southern and eastern coasts of the Island have a drier Coastal Douglas Fir Ecosystem.  In the driest parts of this ecosystem, particularly around Victoria, a sub-class – Garry Oak Meadow – can be found.  This is essentially a temperate savannah, with clumps of oak forest interspersed with meadows and more open prairies.  The Garry Oak is the only native oak tree in Western Canada.  Garry Oak Meadow is now an extremely rare and threatened ecosystem in Canada since most of it has been covered by development in the Victoria area.  The picture below shows a Garry Oak meadow in Uplands Park near Victoria, taken in April when the wildflowers are blooming and before the meadow dries out during the summer drought.    

This type of ecosystem can be found in Oregon’s Willamette Valley, and also stretches down into parts of central California.   Sometimes when I have been driving down in California I will pass through an area of low hills covered with golden grass and clumps of oak trees, and it is striking how much it looks like the undeveloped parts of Victoria in the summer.

The following quote is an indication of how different the natural vegetation in Victoria is from surrounding regions along the B.C. coast.  It comes from Sir James Douglas, the first Governor of Vancouver Island, when he was surveying the region for a potential location for Fort Victoria in February 1843:

“The place itself appears a perfect ‘Eden’ in the midst of the dreary wilderness of the North west coast, and so different is its general aspect from the wooded, rugged regions around that one might be pardoned for supposing it had dropped from the clouds into its present position.”

Douglas chose the site because it was surrounded by so much open meadow and prairie land.  Douglas was visiting Victoria in the spring, and seeing the luxuriant growth of the meadowland, he assumed that the area would be perfect for growing crops through the summer months, writing that  “the climate being also mild and pleasant, we ought to be able to grow every kind of grain raised in England”.   After his first summer in the region, Douglas had learned that Victoria’s dry summers would make agriculture more challenging than he’d originally thought, writing in a letter dated November 1843 that  “no rain fell between the 10th of June and 8th September at Fort Victoria” and that the residents of Victoria were “at times badly off for water”.