Hue lights are designed for indoor use. We test them under certain temperatures and humidity levels to be able to predict how long they will last and make guarantees that they will work. If you use them in other ways than we designed them for they may still work, but we cannot guarantee it. In an outdoor rated luminaire (IP40 and above) there is typically not a problem with water, however heat can build up damaging the electronics in the light. Outdoor luminaires are often made of metal, which can block the Zigbee (RF) signal, making it harder if not impossible to control the Hue light.