Most drones are not designed to get wet, however, they may inadvertently be able to handle a light rain, if not more. If your drone is relatively sealed, with air vents for cooling on the bottom only, some light rain may simply roll off the outside shell of your craft. Your camera may be mounted below your drone, that's a built in umbrella, and your motors may actually be safe for some water as well. Please check with your manufacturer to be sure, but many brushless motors can handle a bit of water running through them, while others may be entirely waterproof, even if the rest of your drone is not. Water is not good for motors, just so we're clear, but long term rust issues may be preferential to an electrical short while in the air. Be safe, don't get your drone wet if you don't have to.