I'm almost certain it would be more usual to
pronounce this 'LOO-na-sa', as in
Lúnasa, the
Irish word for the
month of
August. However, there are almost certainly as many
pronunciations of this
festival as there are
spellings.
Brian Friel's most successful play was entitled
Dancing at Lughnasa.
In Ireland, we still have a holiday around this time, although we now call it the August Bank Holiday. We also have a holiday coinciding with Samhain (Halloween), but we only recently fell into step with the rest of the world in celebrating Bealtaine (May Day).