I've found a temporary fix and it hasn't rained since.
- Finish up everything you want to do for that week and make a MANUAL SAVE.
- Advance to the next week and hop straight into the game, if its still raining then exit to the dynasty hub (hold X/A to skip game intros)
- exit to the main menu and reload your manual save (the previous week) then advanced again and hop into the game. It should be dry but if not you may have to do this a couple times but I only had to do this once and I haven't seen rain all of my season 3
Apparently weather is determined during the advance week screen and weather is locked in once you're in the week, no matter how many times you quit out and load back in. I think the odds of rain must be at 99.9% chance or something for so many people to have this problem. Still. I would rather EA let us pick our own weather, I can get it dry but out of 600+ hours in dynasty in cfb 25 and 50+ in 26 i've only seen snow in maybe 3 games, and I've played as Coastal Carolina, Boise St, Purdue, Colorado & now Delaware.