Jonines, the Lithuanian midsummer festival, is celebrated on June 23, the eve of the feast of John the Baptist's birth. If your name is Jonas, this is your name day.
I really love the name Jonas. It is one of my favorites. I think it can be youthful without being forever young. I also think it can be unique without being too strange. Contrary to popular belief, Jonas ranked in the top one thousand in the USA. I really hope it doesn't get too popular however, because I won't be able to use it on my future son if that happens!
The main character in The Giver, one of my favorite books, is named Jonas. When I first read it, I thought about using the name for my future son if I have one. Then the Jonas Brothers came along... Yup.
In Lithuania and in Latvia, this name is pronounced YO-nas. My great grandfather's name was Valerijonas, and he pronounced the latter part of his name that way. [noted -ed]