The wave master base will be fine outside. It is you are it is a thermoplastic polymer so in time the sun will weaken it so keep it covered when not using it if possible. If in an area which freezes then sand rather than water for the base. Water will freeze and crack the base. The actual 'bag' or striking cylinder is vinyl covered over foam around a thermoplastic inner core that slide off the base. You can always remove it and store inside or keep it covered as will with a tarp of some type. If in a high humidity area mold will grow on it. I live in deep South Louisiana where it is hot and humidity in the 90s most of the year. I have a covered area outside with bags made of the same vinyl material for the past 8 years. If you are a heavy kicker wave masters won't last...everyone I've had we've broken other than those used strictly by kids or beginners.