The body is waterproofed and can withstand rain to some extent. But water may get inside the body during sudden temperature changes such as when it begins raining and the body has been warmed by sunlight.
When using it outdoors, regardless of whether it is waterproof or not, we strongly recommended devices be put into protective cases from which cables and sensors can pass through and measures be taken to prevent water and dust from entering the device.
Waterproof resistance is as follows for various devices:
TR41A: IP67 (Immersion proof)
TR42A/43A: IP64* (Splash proof, rated for use in daily life)
*This is the waterproof capacity of the data logger with the sensor connected. Note that the temperature-humidity sensor is not water resistant.