Rainfall on the “Wet Coast”
February 28th, 2010 | Published in Central Vancouver Island, Natural History
It's always a good idea to bring an umbrella.
One of the questions I often get asked is, “How much does it rain on Vancouver Island? Good question. After all, we live here in a temperate rainforest. And the answer, of course, is “It varies!” But it is a considerable amount.
I pulled out some precipitation data from the Environment Canada Weather Office site. I selected a few communities from up and down Vancouver Island, and on both the east side and the west side. A chart of the data is below.
Monthly Rainfall on Vancouver Island, BC
The trends are quite interesting. Holberg, on northern Vancouver Island, gets close to 4 meters, or 12.5 feet, of rain. Wow! That’s a lot of rain! And Tofino, about a third of the way up the island on the west side gets a similar amount, 3.3 meters or 11 ft. But Henderson Lake takes the cake at 6.6 meters or almost 22 ft of rain a year! All these locations are on the west side of the Island.
An enjoyable wet day at Dixon Falls.
The east side of Vancouver Island is much drier. At 0.83m, Victoria gets about 4 cm more precipitation a year than Toronto. That’s not much. Less than two inches difference considering that both cities get less than a yard of rain a year. It’s less than ¼ of what Holberg gets. About half-way up the east side of the island is Campbell River. It gets more precipitation, about 1.3 m or 4.4 feet. But still much drier than the west side. Port Alberni lies in the middle of the Island at the end of a long inlet or fjord. The precipitation here is about half of Tofino’s. And Tofino is only 80 km away.
Rainfall locations on Vancouver Island, British Columbia.
How does this compare to say, a tropical rainforest like Costa Rica? Simply put, the wettest parts of Costa Rica are about as wet as the wettest parts of Vancouver Island receiving over 6 meters in a year, comparable to Henderson Lake. It rained every day for 359 days in one location. But the driest parts of Vancouver Island are actually drier than the driest parts of Costa Rica.
Enjoying the rain at Weiner Falls.
The lower precipitation levels on the east side of Vancouver Island can be explained by the mountains in the middle of the island. The prevailing winds are from the west. Moisture-laden air is pushed up over the mountains. And in doing this, the air temperature drops and the air cannot carry as much water. It falls on the west side, leaving the air drier when it arrives further east. As the air moves back down the other side of mountain range, it also warms, and it’s ability to hold moister increases. This of course, is called the rain-shadow effect. The further south you get on the east side of the island, the more pronounced this effect becomes. Astonishingly there is a cactus that grows on the southernmost parts of Vancouver Island and on some of the islands in the straight of Georgia, called the Gulf Islands.
Red-legged Frogs like the rain as much as we like them!
The driest months of the year are reliably June, July, August and September. Over the east island, you can count on it raining less at this time of year than in Toronto at this time of year. So unless you want to do some winter storm-watching on the west coast, the time to visit is during these months. Isn’t it handy that it coincides with summer vacations?
About the Contributor:
Long-time Vancouver Island resident, Sandy McRuer, runs Rainbird Excursions, an ecotourism and sightseeing business in the Port Alberni & Qualicum Beach area. He is an ex-forester and avid birder. More of his images can be found on Flickr.
