A number of people have complained in forums about the drop in Web site traffic in summer and weekends. It is certainly a fact. There are not a lot of data about this, but there is at least one published set of yearly statistics showing there is a trough every August. I could not find any data about weekends, so I posted some of my own. My own Web sites are more affected than most by summer traffic depression and perhaps by weekend depression as well. Traffic in May is about 1.8 times that in August.
Here's the article with the graphs: Weekend and Summer Web traffic depression
If anyone has any suggestions about what ought to be done about it, or ideas about long term trends, this is a good place to discuss that.