The middle of August coincides with many things that relate to Hekate. The Nemoralia festival, the Kourotrophos festival, possibly a Deipnon one year, the Ides of Hekate, and loosely the dog days of summer. Nemoralia is however the most likely originator for the modern festivals date.
The things observed in the festival all match with Hekate to some degree – She is associated with storms and protection from storms. She is associated with harvests. She is associated with protection and propitiation. She is associated with crossroads and is often offered to on them.
This festival is based on the dating of an ancient festival (or several of them). It contains aspects that definitely relate to Hekate. But the dates of the ancient festivals do not match those aspects celebrated in the modern festival. So, it’s not an ancient festival, even if it is based on ancient things.
The sheer number of ways that Hekate is connected to this time of year is notable. This may not be an ancient festival, this may be a bit of a mixed bag of a modern festival – but any festival named Hekates Night is definitely on the correct date, whatever its origins and meanings.