Compared to San Diego, you can expect both the days and evenings to be warmer and more humid.  Plus, unlike San Diego in the summer, it might rain although it seems we haven't had rain in months.

Based on your pictures I would say as little as possible!

OK, seriously, this time of year the weather in Boston is very San Diego-like.  Be sure to bring a sweater or light jacket just in case and enjoy your visit!

All good points but it also depends on when you're coming.  For instance, the past few days the weather has been cool in the 70/60's but this week the temps will skyrocket into the 90's with possible oppressive humidity.  Nice and sticky!