We run in the rain. If it's raining when we are going to run, we run. Oh, and if it starts raining whilst we are running, we keep on.
In over 20 years, we have "called" the session due to raun when you could not see the next station. We get those types of rainfalls periodically.
I regularly lube my stuff anyway, nothing special after a rainy running.
I design my conversions to be as well protected from water as I can gtet it, up to and including siliconing the coal pile/oil bunker down tight to the shell.
Worst are diseasemals with open fan grilles. Sometimes I will cut and glue a plug under a fan that has electronics below that point.
You may want to consider voltage losses due to wet ballast on track power.
Can be a whole lot.
But nobody wants to hear that.