You can safely ignore these specs when choosing a graphic tee for hot climates:

• Print resolution: anything above 300 DPI is irrelevant for most designs; you won't notice the difference.
• Number of colors: more colors doesn't mean better quality. It just means more screen setup.
• Print size: a big print covers more area, but it also traps more heat. Smaller prints are often more comfortable in summer.

Focus on the feel, the ink, and the fabric. Those are what determine whether you'll actually want to wear the tee in July.