Ambient Weather Support

Is The Sensor Water Resistant Or Water Proof?

Water proof means the sensor can be submersed in water.

Water resistant means the sensor can be left out in the rain.

The sensor is water resistant but not water proof.
If you want accurate readings, you should keep the sensor out of the sun as it absorbs solar energy.
Thus,  protection from the elements is not required but recommended.
Consider the SRS100LX from placement of the sensor in direct sunlight:

and achieve accurate readings.