Most people know that summer is a tough time to look for a job. Organizations that are usually good networking opportunities shut down for the summer. People who are intending to leave a job in the fall to go back to school or something, choose to take their vacation on their current employer. Recruiters tend not to list new jobs in the summer because they don't think as many people are looking for new jobs in the summer and because it is hard to arrange for interviews. Vacations do interrupt interviewing.
Summer is a GREAT time, however, for making a career plan. You have a little extra time and a little less pressure, so you can think critically about where you are and where you want to be. It's also a good time to get back in touch with people who might be able to help you. They have a little more time in the summer, too.
Most of the year we are so busy, we never stop and think things through. Am I happy with what I am doing? Is there another contribution I should be making? Summer is perfect for that kind of question.
And have fun!