The WiFi Video Doorbell Security Cam is designed for outdoor use, so it is designated to face some extreme weather conditions. Although on a cool day, it can have some temperature on it and it is normal. This is because the device is working. Simply put, when there's no motion at all, the device is in idle mode and it doesn't generate a lot of heat (where call button light is off); when motions are constantly detected which will generate some heat to the device, you will feel the device gets a little hot.
It is Okay to use it under the ambient temperature of -4 ~ 125°F (-20 ~ 50°C). And if the ambient temperature goes below -4°F or above 125°F, please disconnect the power supply to it.