Originally Posted by jackconn
From the factory, we have one vent with MaxxAir (front), one without (rear, over bathroom fan vent). FYI, just yesterday in Black Hills park we left the MaxxAir vent open slightly (maybe 2-3") while gone for the day. Per our usual practice, closed the front vent just in case. Wild thunderstorm passed through (dumped SNOW a few miles up the road!) and we had some spray come in through the vent. Nothing major, but a cautionary tale.
The covers make the vents weatherproof, not waterproof.
If a hard driving rain storm blows in the right direction, they won't keep 'spray' from entering but it will sure help.