Remember you can shut off the sensor power, put the Arduino to sleep, periodically waking up to take a reading then back to sleep.
You will have to worry about ESD and lightning even in a building.
I would imagine ESD is an issue in a building with a lot of dust but still the sensor electronics need to be protected.
Lightning if it strikes in the general vicinity of your silo and electronics will cause a voltage differential as the energy dissipates. It could reach 100's of volts per meter.
Next is to consider how to get the data from the Arduino - Sensor package to where ever you need to monitor it.
You might consider a LoRA Tranceiver. They are really simple to setup and have significant range and are designed exactly for your type of application.