What is Normal Trending

 On my corporate social media site I manage a couple of pages.  The site uses the Jive program which has recently introduced a reporting tab.  It's nice to see the trends but I'm noticing a huge ramp up and then drop off on both of my pages.  One has been around for a couple years the other is fairly new.  One is about starting new projects and the other is about sharing best practices.  Yet both show a very similar trend of participation over the last couple months.

It is important to note that these trend lines show 30 days cumulatively however I makes me wonder if participation is normally higher in July.  Does the summer time and nicer weather get people to contribute more?  This is an internal work only site so I would think all the people taking vacation in the summer would actually push the numbers down.  I've asked some other page managers to see if they have similar results but I would love to know from the outside, do you see monthly or seasonal trends like this?  How do you deal with them?  Is there a way to prepare for the downturn so that it isn't as severe?  Please let me know and I will share any findings I get from this.