Sunday, September 2, 2018

Victoria's Summer of 2018: warmer and drier than average

August 31 marks the end of meteorological summer (June, July, and August), so it's time to take a look back at the summer of 2018 in Victoria.  Overall, the summer was drier and warmer than normal.

Victoria has dry summers, averaging just 52 mm of rain during the June to August period at Victoria Gonzales.  This year, summer was particularly dry, with just 21 mm of rain.  That makes it the 8th driest summer in the past 105 years.  (The driest summer on record was 1970, with just 10.5 mm of rain.)  In 2018, rainfall in June was actually close to average (18.6 mm vs. the average 20 mm), but that was followed by an extremely dry July and August.  There was no rainfall recorded at Victoria Gonzales during July (the sixth time that has happened).  August was also very dry, with just 2.0 mm of rain (all of which fell during a one-hour rainshower on August 11).  August 2018 was the 13th driest on record at Victoria Gonzales, so only about 1 in 8 Augusts have been drier.  This year is notable because the combined July-August rainfall of 2.0 mm was the lowest on record.  Interestingly, the second driest July-August on record was 2017, with 2.2 mm, so we have experienced back to back records for dry July-August periods.

There were 8 days with measurable precipitation this summer, with 7 of those days falling in June.  Victoria typically receives 15 days with measurable rainfall during the summer month (7 in June and 4 each in July and August).  

The chart below shows daily rainfall during summer 2018, and compares the cumulative rainfall with the 30-year average.  June was fairly typical in terms of rainfall, but that was followed by a 41-day stretch with no measurable rainfall from July 1 to August 10.   That's a little longer than the typical drought period that Victoria receives each summer, which averages 28 days.  The only rainfall during the July-August period came during a one-hour rainshower on August 11.  After that, there was no measurable rainfall for the remainder of the month.


Daily & Cumulative Rainfall in Victoria, Summer 2018
The chart below compares the rainfall amounts in Victoria this summer with other locations in the regions.  As is typically the case, Victoria Gonzales had the lowest amount, with a total of 20.6 mm.  Victoria Airport had 27.4 mm of rain throughout the summer, about one third more than Victoria Gonzales.  Although this summer was also drier than normal in Vancouver, it still had about 3 times as much rainfall as Victoria (67 mm at Vancouver Harbour), which is pretty typical.  Rainfall in Seattle was also well below average this summer, and it received just slightly more rain (22.4 mm) than Victoria.   June accounted for the majority of rainfall this summer in all locations.  If you look at just July and August, the difference between Victoria and the other locations is even more stark.  Victoria Gonzales received 2 mm of rain during July and August versus about 6 mm in Seattle and 20 mm in Vancouver.  


Summer 2018 rainfall by month

The mean temperature for June, July, and August at Victoria Gonzales was 16.0 degrees, warmer than the 30-year average of 15.6.  Summer 2018 was tied for the 13th warmest in 105 years of record-keeping at Gonzales, so only about 1 in 8 summers have been warmer.  (Summer 2015 was the warmest on record, at 16.9 degrees.)  June's mean temperature of 14.5 degrees was right on the average.  July's mean of 17.1 degrees was a full degree above the average while August's mean of 16.5 degrees was just 0.2 degrees above average.  This summer, and especially this July, was considered a hot one in Victoria.  However, Victoria Gonzales didn't really experience any extremely hot temperatures.  The warmest maximum during the summer was just 27.2 degrees on August 14 (and the warmest Victoria Gonzales reached in July was just 26.4 degrees).  In fact, the hottest day of the summer this year (27.2) was the 10th coolest on record at Victoria Gonzales, and the coolest since 1982 (that's 36 years).  Typically, the warmest day of the summer at Victoria Gonzales is around 30 degrees.

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during summer 2018, compared with the 30-year averages.  While daytime highs during the first half of June were cooler than average, the rest of the summer was mostly above average, though as noted above, there were no extremely warm temperatures.  Overnight lows were quite consistently close to average or slightly warmer than average.


Average daily max & min temperatures in Victoria, Summer 2018

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