Think that reads off under the timezone you're in. Assuming it's converted the same as thread/post times are for your particular timezone in settings.

Either way it's in the morning assuming that happened in the USA.
Going to assume most of the people that were online at that time were guests since right now it reads: "There are currently 1674 users online. 1089 members and 585 guests"
So it factors in guests as users of the site.
Also going to assume this site was linked somewhere which caused an influx of people.

I look here mainly @ night I believe. So I can't fathom a bunch of people here that early. Someone probably linked directly here from an ad site.
Was a Horny Wednesday it seems.