I'm not experiencing that and I have Forecast installed. However, I'm on 7.1.2.
I don't however, like the fact that the animation seems to play behind the Springboard icons. Without Gridlock and a black background it reveals my iBlanks and totally destroys my iWidgets.
I have an iWidget animated weather tweak that can manage to roll in front of the Springboard icons, yet my icons are still responsive.
The second thing I don't care for is that the animation seems to be a little fast. That may be due to the Weather app though as it's getting the animations from there.
And last but not least, once you've set a zipcode or city there seems to be no way to cancel the animation and revert back to just wallpaper.
I'm actually using it for the falling snow effect to go with my wallpaper for lock and homescreen. I have been trying to find falling snow through Winterboard and none worked. Very happy to be able to have it on this tweak. I love that I can change the effect to what I want, or to the conditions in my city. It's a thumbs up for me. I'm waiting on a few more tweaks and then I will be very content with my JB
Its really cool but when it's running and you quick reply from the lockscreen you get a massive lag in typing. I'm on 6+ and it's super glitchy and I have next to zero other tweaks installed.