Maybe everything is working as intended, but going through the Journey mode on this route is a strange experience. It would seem California is having the mother of all monsoon seasons. I'm half done with this journey, so plenty of runs both ways and I can't remember a single run where there wasn't any rain. Sometimes it starts out pouring and sometimes it starts with clear or with slight cloud but even before I get out of the residential zone i.e. 1/4 of the route, it's usually raining heavily and once it's started it will stay that way for the rest of the run, which is also weird. Not that I have anything against rain but it does get tiresome after a while. Maybe it does pour buckets over there all the time, so it's realistic but I wish I could see a bit more of the scenery every once in a while.
You can just set a custom weather. Dynamic weather is known for giving precipitous weather quite often. Live weather would be better but idk what the limitations would be since it's not been done
