1st August is Lá Lúnasa, the Celtic festival marking the imminent gathering of the harvest.
It is often confused with harvest thanksiving, but with the main crops still in the fields and the berries only just starting to hit ripe, there is not, as yet, anything to be thankful for! Celts tended to look forward... to anticipate events... and hope for good things, whereas the more modern practices emphasize looking back on what we have already achieved and should be grateful for.
You can find out more about the festival, and how the old traditions still play out in modern Ireland, on a new 'Celtic holidays' page that I've uploaded to my website today.