Winter might work well for a boy as well as a girl, though I'd restrict it to a middle name for this use. Generally, the seasons names work better for girls. However, there are month names that might work well for boys, such as March or August. There are also the men's names that spawned certain month names, such as Julius (or Julian, Jules, etc.) for July, Augustus for August, Mars for March, Janus for January, Junius for June. Octavio or Octavian share the same linguistic root as October. The days of the week also come from the names of gods, so you could go for names like Tiw, Odin (or Wodin), Thor...OK, they're a little weird, but it depends on your taste.