Canadian Climate Comparison: which cities get the most and least rainfall?

In the last post, we compared temperatures in the 41 largest urban areas in Canada (those with 100,000 or more people).  In this post, we'll compare precipitation amounts.

The chart below compares average annual precipitation in the 41 largest cities in Canada, ranked from lowest to highest.  The driest city is Kamloops, in the B.C. Interior, with an average of 287 mm annually.  The remaining top 10 driest urban areas in Canada are mostly in the Prairies, along with two more B.C. cities: Kelowna and Victoria.  People are often surprised that Victoria ranks so high among the driest cities in Canada.  Putting this another way, Victoria gets less annual precipitation than nearly 82% of Canada's urban population.  Victoria's low rainfall is thanks to rainshadowing, from both the mountains on Vancouver Island and from the Olympic Mountains in Washington State.  The wettest of the 41 cities is Chilliwack, followed by Vancouver and Abbotsford.  St. John's and Halifax round out the top 5 wettest cities in Canada.  It's striking that cities in Coastal B.C. occupy the top 3 spots for the wettest urban areas in Canada, while nearby Victoria ranks as the 10th driest out of the 41 cities.

Average Annual Precipitation for Urban Areas in Canada

Seasonal variations in precipitation are also important when comparing Canadian cities.  The chart below ranks summer (June to August) precipitation for Canada's cities.  With just 52 mm of rainfall, Victoria is by far the driest urban area in Canada during the summer.  The next driest city - Kamloops - gets nearly 70% more summer rainfall than Victoria, most cities outside of B.C. - such as Calgary, Toronto, or Montreal - get 4 to 5 times as much summer rainfall as Victoria.  The top 6 driest summer cities are all in B.C. - 4 on the coast and 2 in the Interior.  This really shows the impact of the seasonal variation of precipitation in Coastal B.C.  While we just saw that Vancouver ranks as the second wettest city in terms of total annual precipitation, it is the 5th driest city in Canada in terms of summer precipitation.  The wettest summers tend to be in Atlantic Canada and Quebec.

Average Summer Precipitation for Urban Areas in Canada

Victoria also has relatively dry springs - ranking as the 9th driest among Canadian cities.  Fall precipitation in Victoria is closer to the average, with the city ranking as the 17th driest out of 41 cities.  Winter is a different story.  The chart below ranks winter (December to February) precipitation for Canadian cities.  Saskatoon has the driest winters among Canadian cities, with just 37 mm of precipitation.  The top 10 driest winter cities are all located in the Prairies, the B.C. Interior, or Northwestern Ontario.  Victoria ranks as the 31st driest winter city (or the 11th wettest), with 264 mm of precipitation.  The top 5 wettest winter cities are exactly the same as the top 5 wettest cities overall, with Chilliwack in first place with a whopping 659 mm.

Average Winter Precipitation for Urban Areas in Canada

Canadian climate comparison: what is the mildest city in Canada?

This is the first in a series of posts comparing various aspects of climate for locations across Canada, in order to see how Victoria compares.

There are a lot of locations in Canada, so I am focusing on urban areas, where the majority of Canada's populations lives.  I collected climate data for urban areas (Census Metropolitan Areas) with a population of at least 100,000 according to the 2016 Census.  There were 41 such urban areas in 2016, accounting for about 73% of Canada's total population.

This first post is comparing temperatures across Canada.  We'll start by looking at the mean annual temperature for each location.  The chart below ranks Canada's urban areas by mean annual temperature.  Not surprisingly, Victoria ranks first, with a mean annual temperature of 10.6 degrees.  It is followed by Vancouver.  The top 10 includes 5 cities in coastal B.C., 4 cities in Southern Ontario, as well as Kamloops in the B.C. Interior.  The coldest cities are generally those in the Prairies.

Mean Annual Temperature for Urban Areas in Canada

Of course, these annual comparisons mask a lot of seasonal variations among the different cities, so let's look at some of the seasonal rankings.

The chart below compares the mean winter temperature for urban areas in Canada.  This is the mean temperature for December, January and February - which is meteorological winter.  In this case, the coastal B.C. cities really stand out: they are significantly milder than any other locations in Canada.  Victoria's mean winter temperature of 5.8 degrees - the mildest in Canada - is more than 8 degrees warmer than the mildest Canadian city east of the coastal mountains (Chatham, Ontario, with a mean winter temperature of -2.5 degrees).  Even the coolest coastal B.C. city - Chilliwack - is nearly 6 degrees warmer than the warmest city in the rest of Canada.  The top 10 mildest winter cities in Canada include the coastal B.C. cities making up the top 5 spots, as well as two cities in the B.C. Interior, 2 cities in Southern Ontario, and Halifax.  Again, the coldest cities tend to be in the Prairies.

Mean Winter Temperature for Urban Areas in Canada

Victoria also ranks as the warmest Canadian City during meteorological spring (March to May), and the third warmest city during fall (September to November), after Chatham and Windsor in southwestern Ontario.  However, the situation is very different during the summer (June to August), as can be seen in the chart below.  Victoria is the fourth coolest urban area in Canada during the summer: only Calgary, Red Deer, and St. John's are cooler on average.  The top 10 warmest summer cities in Canada include 8 Southern Ontario cities, along with Montreal and Kamloops.

Mean Summer Temperature for Urban Areas in Canada

A brief look at June 2018

I'm a little behind on the blog, so I'm just going to take a brief look at June 2018. 

June was actually pretty close to average this year.  The rainfall at Victoria Gonzales was 18.6 mm, close the the 30-year average of 20.0 mm.  There was measurable precipitation on 6 days in June, again pretty close to the average of 6.8 days. 

While rainfall was very close to average at Victoria Gonzales, other locations around the region recorded somewhat lower than average rainfall amounts (though they still all received more rainfall than Victoria Gonzales).  The Victoria Airport received 23.6 mm of rain in June, below its 30-year average of 30.6 mm.  Vancouver Airport received 38.8 mm, while Vancouver Harbour received 47.8 mm - both below the 30-year average of 54 mm and 70 mm respectively. 

The mean temperature in June was 14.5 degrees, which is right on the 30-year average.  The mean daily maximum for the month was 18.4 degrees, just below the average of 18.5, while the mean daily minimum for the month was 10.6, just above the average of 10.4 degrees.  The warmest temperature of the month was 25.4 degrees, while the coolest temperature was 8.2 degrees.  Again, these are quite typical values for June.