The Chemainus Valley’s gradual transition from winter to spring is just around the corner, but the question right now is which corner? The transition I’m referring to is based on the idea that the meteorological or ecological winter doesn’t shift abruptly into spring like the astronomical or calendar winter.
Instead, it normally changes gradually over a period of a month or two. Ecologists commonly refer to this period as the ‘prevernal’ season, which literally means ‘pre-spring.’ If I can be forgiven for dropping one or two big words, it is one of six non-calendar based bio-meteorological divisions of the year, and is a time when rain, snow, and hardy early-season flowers (particularly the crocus) can all be seen outside at the same time. Any snow that falls during the prevernal or pre-spring period tends to be wet and short lived.
In a normal year on Vancouver Island, this transitional season begins around late January or early February and continues until the arrival of full spring conditions around mid to late March. However, there are no fixed or precise dates for the pre-spring.
In a La Nina year like we’re having now, the prevernal season tends to arrive later in February and sometimes not until early March as was the case last year. It all depends on the strength and location of the Pacific Ocean currents that bring the colder weather. So far, this year’s La Nina currents have been less powerful than last year, and our temperatures have only occasionally been more than a degree Celsius below normal.
Rain and occasional wet snow are expected to continue periodically until early March this year, but the crocus blooms and a few other early season flowers should be very much in evidence by mid-February, which will be about two weeks later than what we would see in a normal year.
By late March, the Chemainus Valley is usually experiencing the change to the full spring or ‘vernal’ season, a period that the rest of Canada doesn’t normally see until mid to late April. This is one of several ecological seasons that are similar to the astronomical seasons, but are given Latin-derived names to minimize any conflict or confusion with the more familiar seasonal names on the calendar.
Similarly, the main summer period is referred to as the ‘estival’ season, the basis of the French word ‘ete’ for summer. Late summer is commonly considered a separate season by ecologists, and is given the name ‘serotinal’, which refers to the time in late August and most of September when many summer plants go to seed. It is also the beginning of the main harvest period that continues into the fall or ‘autumnal’ season.
The ecological winter usually arrives on Vancouver Island around late November, which is about a month earlier than the calendar winter, even in our relatively mild West Coast climate. For the sake of maintaining the pattern of non-calendar based names, this period is usually referred to as the ‘hibernal’ season, the time of hibernation for many plants and some animals.
As we all know, it is accompanied by much rain and occasional snow that can accumulate and stick around for awhile, especially in a La Nina year. Across the rest of Canada, this season can arrive as early as late October. As already mentioned, the hibernal season normally runs until late January or early February on the West Coast, but can last until late March across the rest of Canada.
So if you enjoy gardening, you shouldn’t have too much longer to wait here in the Chemainus Valley. The prevernal season is likely no more than a month away. Just make sure your snow shovel isn’t too far away from your garden shovel when the time comes, just in case!
Chris Carss is a Chemainus resident and a long time weather observer/recorder.