Wednesday, March 3, 2021

A look at Winter 2020-21 in Victoria

Meteorological winter is from December 1 to February 28.  Winter 2020-21 in Victoria brought close to normal temperatures overall, and above average rainfall and snowfall.  

The mean temperature this past winter at Victoria Gonzales was 5.9 degrees, which is just 0.1 degrees warmer than the 30-year average of 5.8.  The average daily maximum for winter 2020-21 was 7.9 degrees (right on the 30-year average), while the average daily minimum was 3.9 (versus the 30-year average of 3.7).  The winter started out mild in December and January, but a cold spell in mid-February brought the overall temperature for the winter much closer to the long term average.  December was 0.9 degrees warmer than average and January was 0.8 degrees warmer than average, but February was 1.5 degrees colder than average.     

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during winter 2020-21, compared with the 30-year averages.  The first half of the winter was generally milder than average, with the exception of a short cold spell in mid-December.  The first half of January was especially mild, but that was followed by another short cold spell in late January.  Temperatures rebounded in early February, only to plunge to the coldest levels of the winter in mid-February, with two days when the temperature did not go above freezing (February 11 and 12).  The warmest temperature of the winter was 14.1 degrees on January 15, while the coldest overnight temperature was -4.0 degrees February 11.

Victoria Gonzales saw 6 days this winter with overnight lows below freezing, versus the long-term average of 9.6 days.  Interestingly, there were no days below freezing until quite late in the winter - February 9 - then Victoria saw 6 days in a row with overnight lows below freezing during the February cold snap, from February 9 to 14.  


Daily Max & Min Temperatures in Victoria, winter 2020-21




Victoria received 380 mm of precipitation from December to February, 42% more than the normal winter precipitation of 267 mm.  December was the wettest month with 157 mm (60% above the average of 98 mm).  January was only slightly wetter than normal, with 111 mm versus the normal 105 mm.  February was also much wetter than normal, with 113 mm - 77% above the normal 64 mm for the month.

Winter 2020-21 also saw more days with measurable precipitation than the 30-year average.  There were 56 days with greater than 0.2 mm of precipitation versus the long term average of 46.4 days.  In other words, there was at least some rain (or snow) on 62% of days during winter 2020-21.  December saw 20 days with precipitation (versus the normal 16.8), January saw 17 days (close to the normal 16.6), and February saw 19 days (versus the normal 13.0 days).  


The chart below shows daily precipitation during winter 2020-21, and compares the cumulative precipitation with the 30-year average.  From about mid-December onward, cumulative seasonal precipitation was well above average.    

December started out relatively dry (with the exception of 18 mm of rain on December 8), but mid to late December saw quite a bit of rain.  This included a deluge on December 21 which brought 55 mm of rain, making ti the second wettest day at Victoria Gonzales in the past 15 years.  Early January was quite wet, followed by a drier period in late January and early February.  The second half of February turned quite wet (and at times snowy).  





The chart below compares the precipitation amounts in Victoria this winter with other locations in the region.  Thanks to the Olympic Mountain rainshadow, Victoria Gonzales is typically much drier than other locations in the region,  but for winter 2020-21, the differences were less than normal, especially compared with Victoria Airport and Vancouver.  That is because Victoria's winter precipitation of 380 mm was 42% above normal in 2020-21, while Victoria Airport and Vancouver were both much closer to normal.  

The Victoria Airport received 402 mm. Typically, the Airport receives 43% more winter precipitation than Victoria Gonzales, but this year the difference was much less thanks to much higher than normal rainfall at Gonzales versus close to normal amounts at the Airport.  Vancouver received 558 mm of precipitation this winter - about 47% more than Victoria.  Normally, Vancouver receives more than double Victoria's winter precipitation, but again, Vancouver was much closer to its normal amount this year, while Victoria was much higher than normal.  Seattle received 510 mm of precipitation this winter, about 34% more than Victoria.  Like Victoria, Seattle was significantly wetter than normal this winter.  


Comparison of Winter 2020-21 Precipitation


Victoria received 28 cm of  snow in winter 2020-21.  That's double the normal winter snowfall of 13.8 cm.  All of the winter snow fell during 4 days in February, with most of it (22 cm) falling on  February 13.  That one February snow event was enough to make it the snowiest winter in Victoria in the past 10 years.  The number of days with snow on the ground was also above normal, but only slightly.  Victoria saw 4 days with at least 2 cm of snow on the ground this winter versus the 30-year average of 3.2 days.

Overall, winter 2020 was  close to normal for sunshine.  However, the seasonal total masks the fact that December was sunnier than normal, while February was cloudier than normal.  Typically, the amount of sunshine during the winter in Victoria increases from December to January to February, but this winter the amount of sunshine was fairly similar in each month.

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) during winter 2020-21.  Overall, the winter total was fairly close to normal, with December having more sunny days than normal, which offset February's fewer than normal sunny days.