There is a saying “While you are resting or messing around, your opponent is training”. The summer period is typically a time when people train less and take it easy. There are less competitions, it’s hot as hell, people go on vacations etc… Don’t get me wrong, enjoy your break and relax, but also set aside some time to work on improving your Jiu-Jitsu for the new upcoming season.

I am a firm believer that the offseason is when you should improve the most. During the season it is harder to consistently lift weights or do extra training sessions since you are already committing a couple of hours a day to training and you still have to manage time for school or work.
The summer gives you time to focus on improving on your weaknesses and preparing for the upcoming season. Maybe last year you felt you could have been a little more technical with your guard, or could of had better conditioning. Now is the time to fix that. Run uphill sprints, swim, rock climbing, do crossfit, drill more, train more often. Basically you should be doing everything that will make you a better BJJ player for the upcoming season.
Eliminate your weaknesses. For example, train one day just back escapes, one day mount escapes, one day pass just on your weaker side etc..
Personally I love the hot and sunny weather. It motivates me to do outdoor sports which indirectly will improve my BJJ game. There are some people that say that if you want to improve your Jiu-Jitsu, you should do only Jiu-Jitsu. In my opinion, training BJJ is the most important but it is good to mix it up and focus on specific weaknesses. If you have faulty cardio, do lots of sparring and train crossfit, do hill sprints. If you feel physically weak, you should be lifting heavy weights doing deadlifts, squats, bench, rows and pull ups, rope climbing etc..
All the hard work will pay off in the end believe me.

Of course for those of you that have had a long season full of competitions and may have over-trained, a 2 week rest is more than recommendable to recharge the aching body and mind. Instead of doing nothing, cross training in any other sport to keep fit is advisable.

For those that are travelling abroad, make sure to bring your gi with you. With the development of BJJ worldwide, you may find an academy where you will be staying. Training with new partners will for sure do good for your game. I personally always try to find an academy wherever I travel either for business or pleasure.

Advisable reading:

Benefits of Swimming
Benefits of Rock Climbing
Benefits of Hill Sprints
Benefits of Crossfit
How to find your optimimum training Mix
How to be more explosive in Jiu-Jitsu
Losing your speed and explosiveness with age? No problem, just change your BJJ game.