Wednesday, September 4, 2019

Summer 2019 in Victoria was statistically normal overall

Meteorological summer runs from June 1 to August 31.  Overall, this summer saw close to normal rainfall and temperatures - it was just very slightly drier and a bit warmer than normal.   However, while June was drier than normal, July and August were both a bit wetter than normal and we experienced about twice as many days with significant rainfall in July and August than we normally do.

Victoria received 48 mm of rain this summer, close to the 30-year average of 52 mm.  Looking at the past 106 summers in Victoria (going back to 1914, when the Gonzales Observatory opened), this past summer ranked as the 52nd wettest – so pretty much in the middle of the pack.  However, this doesn’t mean that rainfall was consistently average throughout the summer.  Victoria received about half of its normal rainfall in June, but then received 33% above normal rainfall in July and 9% above normal rainfall in August.    

While the overall amount of rain was fairly typical this summer, the number of days with significant rainfall was higher than normal.  There were 12 days with more than 1 mm of rainfall this summer, compared with the normal 9.7 days.  Furthermore, 11 of these days were during July and August – the driest part of the summer, which normally sees just 5.3 days with 1 mm or more of rain.  That is likely why this summer seemed a bit more unsettled than the usual in Victoria.  

Another way to look at this is drought periods, or consecutive days without measurable rainfall.  Looking back at summers since 1914, on average there has been a 29-day stretch without measurable rainfall in Victoria.  However, this year the longest stretch was just 19 days – June 8-26.  

The chart below shows daily precipitation during summer 2019, and compares the cumulative precipitation with the 30-year average.   Cumulative precipitation was below average for most of June, but then caught up to normal following a wetter period in late June and early July.  Cumulative rainfall stayed just below normal for the rest of the summer.  The wettest day of the summer was June 27, with 8.4 mm.  Two other days had more than 5 mm – July 2 and August 2.


Daily & Cumulative Rainfall in Victoria, Summer 2019

Compared with 48 mm of rain at Victoria Gonzales during June to August, U-Vic (45 mm) and Esquimalt Harbour (52 mm) had similar amounts, while the Victoria Airport  was wetter, with 72 mm.  The chart below compares the precipitation amounts in Victoria this summer with other locations in the region and across Canada.  Vancouver and Seattle both received about 90 mm of rain.  That was close to normal for Seattle, but well below normal for Vancouver.  Typically, Vancouver receives about 3 times as much rain in the summer as Victoria, but this year it only received about twice as much.  As is typically the case, other major cities in Canada were much wetter than Victoria – generally receiving four to seven times as much rain.  


Total Rainfall Comparison, Summer 2019
The mean temperature this past summer at Victoria Gonzales was 16.0 degrees, warmer than the 30-year average of 15.6 degrees but well below the record warm summer of 2016 when it was 16.9 degrees.  The past six summers have been warmer than average in Victoria.  While June and August were warmer than normal this summer, July was right on the average.  For the summer as a whole, the average daily maximum was 20.0 degrees (just 0.2 degrees above the long-term average) while the average daily minimum was 12.0 degrees (0.7 degrees above the long-term average).   Around the region, the daily average maximum was cooler at Victoria Harbour (18.9 degrees), but warmer at U-Vic (22.2 degrees).     

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during summer 2019, compared with the 30-year averages.  Generally, temperatures stayed fairly close to the long-term averages.  The most significant exception was a short “heat-wave” in mid-June, peaking on June 12, when the temperature reached 30.0 degrees – the warmest day of the summer.  The coldest temperature of the summer was just a few days earlier on June 9, when the overnight low hit 8.6 degrees.

Daily & Average Max & Min Temperatures, Summer 2019

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