It is on the 21st is it not ? I have encountered a few that sat its the day before the solstice and in the UK it is cetainly on the 21st which is the solstice.

I loved the link Summerland and find myself looking forward to Tuesday the 21st because after then the days of the Sun begin to return. though I have gotten off very lightly with my customary SADs this year and been able to maintain a modicum of cheeryness.