Some refer to the summer solstice as "Litha,"
The Reckoning of Time. Bede names "Litha"
as the Latin name for both June and July in ancient times.
So, another little example of Tolkien reviving a bit of old medieval lore and unobtrusively working it in to his own fictions.
just finished: VERY FAR AWAY FROM ANYWHERE ELSE, by Le Guin
just started: THE CATCHER IN THE RYE, by Salinger