Try an all white wallpaper and see if it changes. If it does, then it just doesn't change for the particular wallpaper you are using. If it doesn't change try wiping the cache partition and clearing the apps cache.magerb...
Do you have any idea why my weather info doesn't change?
I assumed you were using the built-in weather widget, my bad! They look identical to each other. Just use the built-in weather widget and it should automatically change for you.I tried an all-white wallpaper, still a white font. I wiped the cache partition, still a white font. Maybe it's the weather app -- "Canada Weather" -- that I'm using.