Originally Posted by
GW11
Canada has a bunch of different climates based on what part of the country we're taking about. The climate in Calgary varies vastly from Toronto. The climate in Halifax varies greatly from that in Saskatoon, you get the picture. Think less about weather conditions and more about humidity or lack thereof.
We're in the middle of the country and our "continental climate" is what makes respiratory virus transmission take such wild swings here. It's the same if you look at Michigan, New York, Pennsylvania, etc. Long, cool dry periods where transmission is high and then long, hot and humid (humidity is key), periods where transmission is low. Look at our summer last year. We had less than 100 cases a day, and it wasn't because people were wearing masks or just got really good at public health measures in the summertime. It's because a humid summer made transmission far more difficult.
The humidity levels on the coastal regions will always keep transmission relatively lower than places with continental type climates.
This is evident if you cross reference humidity trends in a region that is having a "surge" in cases. I looked yesterday, Alberta is "the worst" in Canada right now by the numbers. Their driest point in the season (by RH) is the end of April. Our driest point in the season by RH is March. That's why we peaked in April, same as we did last year.