Can I get seasonal affective disorder during the summer or spring?

Unlikely. Sad occurs in more frequency as you get farther from the equator and typically occurs during those months that daylight becomes shorter. It is believed that with limited exposire to a certain waveband of light, more melatonin is produced resulting in the person feeling lethargic, tired and depressed. With this said, i imagine if you limited your exposure, you could artificially produce this syndro.
Yes. There are some people who develop seasonal affective disorder (SAD) in the spring or early summer. However, the majority of people experience SAD during the fall or winter.