Summer is also the conference season. We have conferences and workshops year round but many organizers like to have their conferences in the summer when they won't conflict with courses. Instead we have conferences conflicting with each other. Be careful that you don't want to go to too many conferences as they cut into your the summer relaxed research atmosphere.
I plan to attend at least two conferences this summer, STOC, which starts this weekend in the beautiful suburbs of Baltimore and, of course, the Conference on Computational Complexity next month in San Jose. Stop by and say hi if you are there.
It's not summer yet in Chicago. We run in quarters at the University of Chicago and have two more weeks of classes followed by finals week. I can go to STOC missing only one day of classes but there were some conferences and workshops later on I will have to skip for finals week and graduation.
We get our revenge in the fall where most universities start at the beginning of September or earlier and our classes don't start until the last week of September. We hardly see any conferences scheduled in September, particularly in the US, because it is the beginning of most universities semesters. So I use September to visit faculty at other schools. We used to take vacations in September (crowds are smaller everywhere) but now the kids have school starting in late August making our effective summer quite short.