Yes, those are some big jumps in August.
Peak figures are unreliable due to how they are counted. When a JW puts their July and August report in at the end of August, the WTS does not update July, they count it as two publishers for August. As August is the last month of the service year, and the service overseer tries to get all the forgotten reports in for previous months, there is usually a spike in that month.
Average reports are more reliable as the spikes are evened out. However, even these are suspect. For instance, a couple of years ago publishers could start reporting even if they only did 15 minutes in a month. We also know that many JWs that don't believe report just to keep the elders off their backs. Still, average stats will be at least somewhat more accurate than peak stats.