24th June is Midsummers Day. I have often wondered why Midsummers Day celebrations are not at the same time as the Equinox. Afterall the Equinox celebrates the sun being at its most northern point and most Northern part of the world have celebrated it in some way or other since Neolithic times.
As usual the confusion arises in Roman times when Christianity started absorbing pagan festivals. In celtic regions the festival of Litha celebrated the equinox. In Romean Empire there were festivals to Fors Fortuna (the goddess of good fortune) which was believed to be an 8 day festival and it was also sacred to Juno the wife of Jupiter and goddess of women and childbirth. The month of June was named after her and because Juno was the patroness of marriage, June has always been a popular time to marry.
However Christians designated 24th June as St. Johns day in commemoration or St. John the Baptist and overtime the 8 day roman festival, the pagan Summer Solstice festivals and St. Johns festival were all celebrated around the same time in different northern countries by different religions. Specifically the Northern European celebrations that accompany the actual solstice take place on a day between June 19 and June 25 and the preceding evening. The exact dates vary between different cultures and the observance of St John's Day begins the evening before, known as St John's Eve. In Sweden Midsummer is particularly important and they are considering making it a national holiday.
Further Information
This time of year was always considered magical by the Celts especially in Cornwall and Ireland, when there was feasting, fires, songs, and dances could last for days. Bonfires were kindled on high hills to commemorate the high point of the year. Wheels of fire would be rolled down the hill into water to signify the turning of the year and the sun going down. Another possibility is that the water mitigates the heat of the sun, with the sun wheel being put out by water may prevent drought.