@KentishKen 

It needs something like this. 

https://www.reddit.com/r/Aqara/comments/t5gkuo/made_a_weatherproof_enclosure_for_doorwindow/

  @KentishKen 

A cheap way to get a waterproof cover for a sensor is a junction box of
the type used in electrical installations. The IP code tells what type
of water-protection you get. IP55 or IP65 means spraying with a garden
hose is OK. Sensor in the box and magnet outside. I'm doing this for a
mailbox to avoid unnecessary going outdoors when it is empty.

After almost six months use the "status report" is that this solution
works exactly as intended. Very heavy rainfall and storm-winds have
not had any bad influence at all.

To detect even the smallest opening of the mailbox hatch the mechanical
linkage to the magnet had to be adjusted once. I use a smaller (and weaker)
magnet to match the smaller movement available, 20 mm in my case.
(Depends on the item you want to get sensor signals from.)

The junction box I use is 90 x 90 x 60 mm, black and very discreet.

Now I only have go out in the rain when I know mail has arrived.