This Farmer's Almanac article has a lot of the "magical" listed...
which helps explain why the summer solstice and Midsummer's Day are different and why Midsummer's Day varies both in date and in ways of celebration between countries.
When I was a kid, St John the Baptist Day was commonly celebrated in Texas with bonfires on the eve before - but a five year drought in 1950's ended that here - it is still celebrated in Ireland.

https://www.farmersalmanac.com/midsummer