To avoid any light problems (e.g. the field on which you're playing is darkened), use these steps and you'll enjoy any NEW added stadium, without having to replace an existing one.
1. Open the game's database file using DB Master 12.
2. Search for the stadiums table.
3. Search the stadium that you've just added (after ID or after its name).
http://postimg.org/image/mpyyj2ltz/
4. Go at the end of the columns and search the column named
isdynamic.
5. Change the 0 number to 1. If the number is already 1, leave it that way, because you don't need to change it to 0!
http://postimg.org/image/y4wrgeoir/
6. Save the database.
7. Open the game and choose your new stadium and at the "weather" option DON'T choose clear (as you can see in the picture below)! Overcast, Rain and Snow works perfectly, but not the clear weather.
http://postimg.org/image/rgl3jjzxx/
8. If your new stadium doesn't have at least the "overcast" weather, open up the game's database using DB Master 12, go to stadiums table, choose your stadium and search for the
tod1weather column. If you see any number there,
change it to 3. Save the database and test it in your game. Now you can see by yourself that IT'S SNOWING!
I hope this will help some of you guys and you can enjoy any new stadium added in FIFA 13!
Cheers!