Just like in MSFS you have the ability to change your time & day while in game , I hope they can eventually implement this feature into TSW someday.
I don’t think DTG has the same access to the raw weather sources or the computing power that Microsoft and Asobo have to produce the weather used in MSFS2020…. And even then the MSFS3020 forums are full of complaints the the simulation weather does not match the real WX people are experiencing. WX is a major fracturing fir flying especially fir General Aviation aircraft where temperature and humidity great affect flight characteristics. Not that much of a factor in driving a locomotive.
Adding real time weather would not be too difficult. DTG does not add it because they think people prefer weather that changes more frequently than in real life. I mean, if it is raining IRL at 10:00 in London, it will probably still be raining at 10:15, at 10:30 and at 10:45. If it changes it will probably not change much (maybe it rains, then you have heavy clouds, then rain again).
It would be a neat feature. I believe Polyphony Digital was going to implement something similar for GT7 but backed out. If I want this I just crack open my weather app and look up the weather in Frankfurt or Glasgow and set accordingly.
Automobilista2 has this feature, with an archive for historical weather i look out of the window and then select the weather. Unfortunatly dynamic weather is realy limited in options.