Is door-open sensor waterproof?

Technically the entry sensor itself is not weatherproof, the little magnetic part is but the actual sensor no. Now there has been videos on YouTube where people were making things that the sensor will slide into to make it weatherproof so might want to check YouTube out and see if you can get any ideas.

And others have suggested putting it in a baggie or some sort of clear plastic, to protect from rain (as in, in an open porch, under an eave) - just have to be careful with added moisture inside the baggie/plastic.  Remember weather elements, and range distance when you are using anything outdoors (and battery will struggle in extreme weather) - and be sure to test your sensors in Test Mode and live mode if you are depending on their use outdoors.

Ebay has plastic covers designed to protect the sensors from rain