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.

A look at Spring 2018

Meteorological Spring (March to May) is now over, so it's time to look back at the spring of 2018.

Overall, this spring was slightly warmer than normal, with a mean temperature of 10.4 degrees versus the 30-year average of 10.0 degrees.  This spring was still cooler than spring 2014, 2015, or 2016.  Spring 2016 was the warmest on record in Victoria, with a mean temperature of 11.9 degrees.

The chart below compares daily maximum and minimum temperatures with the long-term averages for Victoria Gonzales.  Generally, temperatures have been close to average, expect for a spike in late April and again from May 5-15.  March was slightly below average temperatures, April was right on average for the month, and May was above average.

Daily Max & Min Temperatures at Victoria Gonzales, Spring 2018

Spring 2018 precipitation was a bit below average.  Both March and May experienced well below average rainfall, but April was much wetter than average.  The chart below shows daily and cumulative rainfall for March to May 2018 at Victoria Gonzales.  You can clearly see the very wet spell in April, especially from about April 4 to 16.  This less than two week period accounted for nearly two thirds of all the rain during Spring 2018.

Daily and Cumulative Rainfall at Victoria Gonzales, Spring 2018

A warm and dry May in Victoria

May 2018 was warm and dry in Victoria, but there were no monthly records set.

The mean temperature for May 2018 was 13.6 degrees at Victoria Gonzales, significantly warmer than the 30-year average of 12.4.  That was tied for the 8th warmest May out of 105 years on record at Victoria Gonzales.  In other words, May was warmer than average, but not record-breaking.  The warmest May at Gonzales was 14.2 degrees in 2005.

The average daily high and low temperatures for May 2018 were 17.5 degrees and 9.8 degrees, in both cases more than one degree above the normals of 16.3 and 8.4 degrees.  The warmest temperature of the month was 25.2 degrees on May 13th.  The coolest temperature was 7.5 degrees on May 2nd.

The chart below shows the daily maximum and minimum temperatures this May compared with the long term averages.  Temperatures were above normal for most of the month, but especially from about May 5-15.

Daily Max & Min Temperatures at Victoria Gonzales, May 2018

Following a wet April, May was dry in Victoria with just 8.8 mm of rainfall at Victoria Gonzales, about one third of the 30-year average of 28 mm.  This was the 15th driest May on record at Victoria Gonzales (with records going back 105 years), so again, while it was drier than normal, it wasn't really too unusual.  The driest May on record in Victoria was 1.8 mm back in 2015.

Victoria's entire May rainfall in 2018 all came on one day, May 10.  On average, Victoria gets 9 days with measurable rainfall in May, so having just one day with rainfall is well below the average.  The chart below shows the daily and cumulative precipitation in Victoria this May, compared with the average cumulative precipitation.  Clearly, rainfall was well below normal.  There was no measurable rainfall during the last 21 days of the month.

Daily and Cumulative Rainfall at Victoria Gonzales, May 2018

While Victoria typically gets less rainfall than other locations in the region, that was not the cast this past May.  While Victoria Gonzales received 8.8 mm of rainfall in May, there was only 3.4 mm of rain at the Victoria Airport.  Typically, the Airport receives about one third more rainfall than Victoria Gonzales in May.  The comparison with Vancouver was even more unusual this year.  Normally, Vancouver receives about three times as much rain than Victoria in May (85 mm versus 28 mm), but in 2018 Vancouver's May rainfall was just 1.6 mm.

A wet April in Victoria

As was the case in March, April in Victoria had close to normal temperatures, but while March 2018 was much drier than normal, April 2018 was much wetter than normal.

The mean temperature for April 2018 was 9.9 degrees at Victoria Gonzales, right on the 30-year average.  The average daily high temperature of 12.9 degrees this year was half a degree below the normal of 13.4, while the average daily low temperature of 6.8 degrees was half a degree above the normal of 6.3 degrees.  The warmest temperature of the month was 24.9 degrees on April 26th.  That's the fourth warmest monthly maximum temperature ever recorded at Victoria Gonzales, with the warmest being 27.0 degrees in April 1998.  Victoria Gonzales averages about 1 day in April with maximum temperatures above 20 degrees; this year there were 3 days.  The coldest temperature was 2.5 degrees on April 2nd, which is a fairly typical monthly minimum for April.

The chart below shows the daily maximum and minimum temperatures this April compared with the long term averages.  Generally, temperatures have fluctuated around the averages, although you can see a period of below average temperatures mid-month, followed by a mini-heatwave that occurred April 23-26.

Daily Max & Min Temperatures in Victoria, April 2018

While temperatures were close to normal, precipitation was well above normal, with 62 mm of rainfall at Victoria Gonzales in April, nearly double the 30-year average of 33 mm.  This was the ninth wettest April on record at Victoria Gonzales (with records going back 105 years).

The chart below shows the daily and cumulative precipitation in Victoria this April, compared with the average cumulative precipitation.  Clearly, rainfall was well above normal, particularly in the first half of the month.  There was measurable precipitation (more than 0.2 mm) on 15 days this April, compared with the normal of 10 days.  The wettest days were the 4th (when 13.2 mm of rain fell) and the 16th (12.2 mm).

Daily & Cumulative Rainfall in Victoria, April 2018

As is typical, other locations in the region were even wetter than Victoria Gonzales in April.  The Victoria Airport recorded 98 mm of rain in April, while Nanaimo recorded 113 mm (about double Victoria).   Vancouver Harbour recorded 179 mm of rain in April - nearly three times as much rain as Victoria, which is fairly typical.  Seattle recorded 145 mm of rain in April.

Winter in April

Despite all the flowers blossoming around town, yesterday was a very winter-like day in Victoria.  The high yesterday was just 6.7 degrees.  That's more than 5 degrees below the normal high for April 4 of 12.2 degrees.  That's even below the average 7.2 degree high for December, Victoria's coldest month.  It was definitely chilly!  There have only been two April days in the past 50 years that were colder than yesterday.

It was also quite wet, with 13.2 mm of rain.  That's about 40% of the normal rainfall for the entire month of April.  It seemed especially rainy after the dry March that we just experienced.  In fact, the 13.2 mm of rain yesterday was almost as much as the 13.6 mm recorded in the entire month of March this year.

The normal average high temperature for April is 13.4 degrees, while average rainfall is 33 mm with measurable precipitation on 12 days.  Rain is recorded at Victoria Gonzales 11% of the time during April, while sunshine is recorded 52% of daylight hours.  Hopefully, we'll get back into our more typical warmer, drier and sunnier April weather soon!