Owing to the Earth's axial tilt, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice (typically June 21 UTC) through to the September equinox (typically September 23 UTC).
The next time we should expect to see some interesting
BTC price highs should be between December and January... and the lows between June and October.
Miners can weigh in on this, perhaps...