Jazzz, sure some of the things you said must play some role in mitigating/preventing if that's what happened. But just to continue my thought...

Seasonality can go as far back to November, December because althought UV and temp could play a role in slowing the virus it's also important to factor in people's behaviours such as spending more time inside. If the wave peaked in December from seasonality then I would say it doesn't necessarily mean you're going to see a guaranteed surge following right after that in Jan-Feb, because natural wave progression makes it harder to bring up another wave within such a tight period of time. Though an exception to that might be if a variant took off.