Advice for Weatherproofing?

Our sensors were damaged when it rained here in Los Angeles, and we’re not sure if it was due to changes in air pressure or simply water damage. How can we weatherproof the sensors so that this doesn’t happen again?

What model sensor, and what kind of damage did you experience?

The model is: Purple air Classic air quality monitor - PA II
I’m asking on behalf of someone else, so I’m not sure exactly what the damage was like other than the fact that the sensors did not work after the rainfall.