Summer 2023: warmer and slightly drier than normal

 Meteorological summer consists of June, July, and August.  Summer 2023 was warmer and a bit drier than normal.

The mean temperature this past summer at Victoria Gonzales was 16.4 degrees, which is 0.7 degrees above the 30-year average.  Summer 2023 was tied for the 6th warmest in Victoria since record-keeping began at Gonzales Observatory in 1914.  Temperatures got warmer as the summer progressed: June was close to average, July was 0.5 degrees above normal, and August was 1.4 degrees above normal.  In fact, August's mean temperature of 17.8 C was the warmest on record at Victoria Gonzales.

The average daily high temperature this summer was 20.7 C (versus the normal of 20.0 C) while the average daily minimum was 12.0 C (normal 11.5 C).   

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during summer 2023, compared with the 30-year averages.  The first half of the summer had a mix of both below and above normal temperatures, while the second half of the summer saw mostly above normal temperatures.  The warmest temperature of the summer was 32.5 C on August 19th, which was also the 10th hottest August day ever recorded in Victoria.  It was the only day of the summer to exceed 30 C.    

The coolest temperature during the summer was 8.5 C on June 19th.

Daily Max & Min Temperatures in Victoria, Summer 2023

Victoria received 35.4 mm of rain from June to August, about three-quarters of its normal summer rainfall of 47 mm. While it was drier than normal, it was not usually so: summer 2023 was just the 41st driest summer in Victoria in the 125 years of record-keeping.  Just two days accounted for 70% of the summer's rainfall: June 10th (13.2 mm) and July 24th (11.4 mm).

Victoria had only 8 days with measurable rainfall this summer, compared with the normal 14.8 days.  There were 3 days with measurable rain (>0.2 mm) in June, 1 in July, and 4 in August.  

The chart below shows daily precipitation during summer 2023, and compares the cumulative precipitation with the 30-year average.   While rainfall was very sporadic, the cumulative rainfall generally kept fairly close to normal throughout the summer.

Daily & Cumulative Rainfall  in Victoria, Summer 2023

Summer 2023 sunnier than normal.  June and July were both sunnier than normal, while August was close to normal.  

The table below shows the number of mostly sunny days (>80% of possible sunshine), partly cloudy days (20-80% of possible sunshine), and mostly cloudy days (<20% of possible sunshine).  Summer 2023 was very sunny, with significantly more mostly sunny days than normal (62 in 2023 compared with the normal of 45 days).  There were also fewer mostly cloudy days than normal (10 days compared with the normal of 12).  July was a particularly sunny month.

An extraordinary drought

 Victoria is known for its summer droughts.  It is the driest major city in Canada - by far - during the summer months, with an average of 47 mm of rain during June to August combined.  It is also common to get long stretches with little or no rainfall during the summer.  On average, Victoria gets 31 consecutive days with no measurable rainfall each summer, and 42 consecutive days with less than 1 mm of rainfall.

However, the past three months have really been extraordinary.  From July 19 to October 20 - a period of 94 days - there have only been 3 days each with just a barely measurable 0.2 mm of rain (August 10, September 4, and September 28) at Victoria Gonzales.  That's a total of just 0.6 mm of rain in the past 3 months!  The nearby weather station at the University of Victoria has been even drier, with just 0.4 mm of rain over the same period.

This has been the driest 90-day period ever recorded at Victoria Gonzales, as shown in the chart below, easily beating the old record of 2.8 mm, from May 25 to August 22, 1951.  Note that most of these record dry periods tend to be centered on July and August, the two driest months in Victoria.  However, 3 of the 11 driest periods, include this year's, have extended into mid-October.

This record-breaking drought has not just impacted Victoria; it has affected all of southwestern B.C.  The chart below shows the total rainfall for various locations in southern B.C. over the past 3 months. As is often the case, Victoria has been the driest location, but most locations have been extraordinarily dry.  Keep in mind, that normal rainfall during this period is 91 mm at Victoria Gonzales and 231 mm at Vancouver Harbour.  

Not only has this period been the driest 3-month period ever recorded in Victoria (with 120 years of record-keeping at Victoria Gonzales), but it is also likely the driest 3-month period ever recorded in any major Canadian city.  The driest 3-month period ever recorded for some other Canadian cities includes 1.3 mm for Edmonton, 2.9 mm for Calgary, 6.1 mm for Vancouver Airport, and 37.9 mm for Toronto

In addition to being dry, it has also been a very warm 3 months.  The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during the drought period (July 19 to October 19), compared with the 30-year average.  With just a few exceptions, temperatures have been above normal.  The average daily maximum temperature for the period was 21.3 C -  nearly 3 degrees above the historical average of 18.4 C.  In addition, the average daily maximum temperature for the period in 2022 (21.3 C) is more than 1 degree warmer than the previous highest average maximum of 20.1 C for the same period in 1998.

Victoria Gonzales Daily Max & Min vs. normal

Victoria records 53 days with no measurable rainfall - the third longest such dry streak on record

 Following the unprecedented heat wave in late June 2021, temperatures in Victoria returned to normal, but the dry sunny weather continued.  

Victoria Gonzales received no measurable rainfall in July.  That is the 7th time that Victoria has experienced a July with no measurable rain (the other times being 1914, 1922, 1926, 1958, 1984, 2018).  It is also the 12th time overall that Victoria has had a calendar month with no measurable rain.  

In all, there was no measurable rain recorded at Victoria Gonzales from June 15 to August 6 - a total of 53 days.  That makes it the third longest such dry streak recorded in Victoria over the past 120 years.  The longest dry streak was 63 days, from June 15 to August 16, 1926.  The second longest was 54 days from July 17 to September 8, 1986 - many residents will remember that year for the great weather at Expo 86.  

The chart below shows the longest dry streaks ever recorded in Victoria.  Of note, 4 of the 10 longest dry streaks occurred in the 1920s, which was the driest decade on record in Victoria for both average annual precipitation (601 mm) and average summer rainfall (34 mm for the June to August period). The past 10 years (2011-20) was the second driest decade for summers, with an average 36 mm of rain, which could indicate the beginning of a trend towards even drier summers that most climate models predict for our area as a result of climate change.  Conversely, none of the longest dry streaks was in the 1990s, which was one of the wettest decades (along with the 1930s) in Victoria, for both total annual precipitation and summer rainfall.  

Victoria's advantage when the weather is unsettled

We're currently into a perfect stretch of warm, dry and sunny summer weather: take a look at the forecast for Victoria for the next week.

However, it seems like earlier in the summer the weather was a bit more unsettled than usual, especially in June and the first half of July.  While we might complain when the weather's not perfect in the summer, we should remember that compared with other locations in the region, Victoria's weather actually stands out the most when the weather pattern is a bit more unsettled.  When we have a strong ridge of high pressure giving us the sunny weather we're currently experiencing, other parts of the B.C. south coast are usually experiencing similar conditions.  It's when the weather's unsettled that Victoria's climate really shines.  Unsettled weather during the summer might mean a little more cloud and a chance of sprinkles in Victoria, while in other parts of the region they are getting much more cloud and rain.

Let's start by comparing the rainfall in Victoria and Vancouver this summer.  The chart below compares monthly rainfall from May up until today (August 14) at Victoria Gonzales and Vancouver Harbour (downtown).  You can see that Vancouver has clearly had a LOT more rain.

Summer 2016 Monthly Rainfall, Victoria vs. Vancouver

On average, Vancouver gets about three times as much rainfall from May to August than Victoria (240 mm vs. 80 mm).  This year, Vancouver has had five times as much rain as Victoria (224 mm vs 45 mm).

The chart below compares the total May-August 2016 rainfall (up to August 14) at Victoria Gonzales with several other  locations in the region.  Although the Victoria Airport usually gets about 35-40% more rain than Victoria Gonzales during the summer, this year it's been almost as dry.  However, Vancouver Airport (located in a relatively dry part of the Vancouver region) has had more than three times as much rain as Victoria, and as we've seen, Vancouver Harbour has seen five times as much rain.  Nanaimo, Comox, and Campbell River - which normally get about twice as much rain as Victoria during the summer - have received nearly three times as much rain as Victoria this summer. Finally, Seattle Airport - which normally gets about 60% more rain than Victoria during the summer - has received about double Victoria's rainfall this summer.

Total Rainfall, May to August 2016

So during this somewhat unsettled summer, other locations in the region have received even more rain relative to Victoria than they normally do.  We might grumble sometimes when we get a patch of unsettled weather in the summer instead of the endless sunny days that we expect, but we should keep in mind that when it's unsettled here in Victoria, it's probably still a lot better weather than other parts of the region.

While we're talking about the rainfall amounts this summer, I'd just like to comment on another case of it all being relative.  We've heard in the news that Southern Ontario is experiencing a severe drought this summer.  In Toronto, they have received just 45% of their normal rainfall since the beginning of May.  Sounds pretty dry, doesn't it?  The thing is, normal May-August rainfall in Toronto is 300 mm, so 45% of that is 135 mm - or about three times as much rain as Victoria has seen over the same period.  For Victoria, 135 mm of rain during May to August would be an unusually wet summer, and certainly wouldn't be considered a severe drought!  In fact, in 117 years of record-keeping at Victoria Gonzales, there have only been five summers where our rainfall totals have reached 135 mm.  As I said, it's all relative!