Most Strips have a protected enclosing that protects them from outdoor conditions. However, this is NOT the case for the sensors with holes in them, like the Comfort 700 for Z-Wave and the +Comfort and Presence sensors for LoRaWAN.
Strips Guard is designed to be mounted between a window/door and its frame. This means it will be subject to conditions that can be a bit damp and with varying temperatures.
Being weatherproof means that Strips has been designed to withstand these conditions.
However, it is NOT waterproof, a big difference. You should NEVER set Strips someplace where it will come in direct contact with excessive amounts of water and mounted protected from the worst extreme weather conditions, like hefty rain.