In July, are you able to snowboard or is that when the weather starts to become too hot?

Sure just bring your own snow bra.....jk, Mammoth Mtn might still open though. They were open 288 days last year

The season is normally over by March. During the El Nino storms, it can last up to April. Bear Mountain reopens for mountain biking or sight seeing/hiking.

Try wakeboarding in july

Usually snowboarding is not possible in July. The temperatures right now are in the 70's here in Running Springs.