Is anyone else experiencing this on Xbox?. I'm currently working my way through Edinburgh Glasgow in journey mode and any time it starts to rain you can hear it but you can only see it when pulling into a station. Whilst in the station it falls onto the windscreen and you need the wipers to clear it but as soon as you set off again you dont and you get about 300 yards out and the rain stops but you can still hear it and see lightning. This repeats for each station.
There's a known issue with the driver's side windscreen not reacting to rain or snow. I'm sure your post falls into this category
Sounds like the windshield is set up wrong and the game thinks it's at an angle that prevents raindrops from forming on it while moving? Like there are trains with really straight, vertical windshields where you won't have much rain drops on it when stationary, but get more as you are moving - due to the train hitting the raindrops. In this case it's the other way around. The game must think that the windshield is at an angle that causes it to miss the raindrops when moving? Just a guess. But not the first time a TSW loco had a similar issue like that.
I did a run the other day on SEHS in TSW2 and it was snowing in June. So I guess anything can happen in the wacky wonky world of TSW
