Not all speakers are suited for being installed outdoors. Outdoor speakers have to meet a number of requirements. I will offer a brief checklist to help you ensure that the speakers that you are preparing to purchase will last a long time in an outdoor environment. Following these tips may save you a lot of money in the long run.
Probably the most difficult problems facing outdoor speakers are the harsh conditions in terms of the changing climate. Humidity requires that the speaker enclosure be made of a material that can tolerate water. The majority of speakers speakers for outdoors are made of a plastic material. Further, the enclosure has to be properly sealed to avoid water from creeping inside. If the speaker is wireless than chances are that water inside the speaker will damage the sensitive electronics. Therefore, there should be no obvious gaps or cracks. Also, any control elements and buttons should be covered with a water-proof material.
Another important requirement is that the enclosure material can tolerate extreme temperatures and sunlight. Even though you never want to mount the speaker in direct sunlight, chances are that nonetheless it will be exposed to the sun for part of the day. Thus the material should be able to tolerate UV rays.