The two most important external factors to consider when using hot melt glue are temperature and weight.

Hot melt glue is not ideal in very high-heat or cold environments, especially since hot glue can break in cold weather. This breaking temperature can depend on the specific hot glue you are working with, so it can be worth checking before use.

A silicone sealant may be more durable in cold temperatures, but you should keep in mind that it will take longer to cure.

Hot melt glue is rarely used for high-strength applications. The exact weight it can handle will depend on the material and glue being used.