Tuesday, September 1, 2020

Summer 2020: Average rainfall but cooler than normal

Meteorological summer consists of June, July, and August.  Summer 2020 in Victoria brought cooler than normal temperatures and normal rainfall.  

The mean temperature this past summer at Victoria Gonzales was 15.3 degrees, which is 0.5 degrees cooler than the 30-year average.  Summer 2020 was the coolest in Victoria since 2012.  All three summer months were about 0.5 degrees cooler than normal.     

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during summer 2020, compared with the 30-year averages.  Aside from the occasional short "heat wave", temperatures were generally below average for most of the summer, particularly in early July.  The average high temperature at Victoria Gonzales for summer 2020 was just 19.1 C (17.6 C in June, 19.7 C in July, and 19.9 C in August).  Other locations in the region, away from the cooling effects of the Strait of Juan de Fuca, were warmer.  For example, the average daily high temperature this summer was 20.8 C at Oaklands School, 21.8 C at U-Vic, and 23.3 C at Millstream Elementary in Langford.


Victoria Gonzales averages 38 days each summer when the temperature exceeds 20 C, but for summer 2020 there were only 26 such days: 5 in June, 13 in July (all during the second half of the month), and 8 in August.  There were only 4 days above 25 C in summer 2020 compared with the average of 7.  There were no days when the temperature exceeded 30 C, compared with the average of 1.1 days.  It did exceed 29 C twice: once in late July and again in mid-August.


Daily Max & Min Temperatures in Victoria, Summer 2020



Victoria received 47 mm of rain from June to August, which is exactly normal for the summer period. June was slightly wetter than normal, July was slightly drier, and August was very close to normal rainfall.  

While the amount of rain during summer 2020 was normal, the number of days with measurable rainfall was higher than normal.  Summer 2020 saw 18 days with measurable rainfall (9 in June, 3 in July, and 6 in August) compared with the average of 14.7 days that Victoria usually sees during the summer.  The longest dry spell was 22 days, from July 12 to August 2.  By comparison, the average summer drought period over the past 30 years has been 26 days.


The chart below shows daily precipitation during summer 2020, and compares the cumulative precipitation with the 30-year average.   June and early July started out slightly wetter than normal, but by the end of the summer, total rainfall was right on the 30-year average.  The highest rainfall amount was 7.8 mm on June 9.


Daily & Cumulative Rainfall in Victoria, Summer 2020


The chart below compares the rainfall amounts in Victoria this summer with other locations in the region.  As is typically the case, Victoria Gonzales had the lowest amount, with a total of 47 mm.  The Victoria Airport received 75 mm - nearly 60% more than Victoria Gonzales.  Normal summer rainfall at the Victoria Airport is 67 mm.  Vancouver received 145 mm - more than three times as much as Victoria, which is fairly typical.  Seattle received 97 mm - more than double Victoria's rainfall.  However, most of Seattle's summer rain fell in June, while July and August were actually slightly drier than Victoria.  

Rainfall by location, Summer 2020

Summer 2020 was slightly sunnier than normal.  While June was a bit cloudier than normal, both July and August were sunnier than the long term average, with Victoria receiving around 74% of possible sunshine during those months.

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).  June had only 8 mostly sunny days, compared with the 30-year average of 11.5.  July (19 mostly sunny days) and August (18 mostly sunny days) each had two more sunny days than the 30-year average.