In the sixth book of the Fasti the goddesses argue over the month. Juno claims Iunius outright as her own, queen of the gods and patron of marriage; Juventas, goddess of youth, counters that the month honours the iuniores, the young men of fighting age, as May honoured the maiores, the elders; and Concordia proposes that the name records the joining, iungere, of the Romans and Sabines into one people. Ovid, as he did for May, declines to judge between them, and the derivation of June remains as open in modern scholarship as the poet left it.
The religious centre of the Roman month was the hearth of the state. The inner sanctum of the round temple of Vesta stood open to the city's married women from the seventh to the fifteenth of June, the only days of the year they could enter it barefoot with their offerings, while the Vestals cleansed the temple and carried its refuse away down the Tiber. Until that cleansing was complete the days were held religiously unfit for weddings, which is the root of the old preference, recorded by Ovid and long outliving Rome, for marrying in the second half of June rather than the first. The Matralia of the eleventh, the festival of Mater Matuta, belonged likewise to the women of the city.
June's bee keeping, haymaking calendar of saints' days in medieval Europe hung around the nativity of John the Baptist on the twenty fourth, the one saint's birth besides Christ's and Mary's that the church calendar keeps, placed half a year before Christmas at the sun's other turning.
Sources FastiOvid with Rome's Vestal Virgins: A Study of Rome's Vestal Priestesses in the Late Republic and Early PrincipateRobin Lorsch Wildfang, The Oxford Dictionary of the Christian Church, 3rd revised editionF. L. Cross and E. A. Livingstone (eds.)