The weather is just one thing they got wrong. It's a long list.
No one knows how long this war will last. At this point Russia seems unable to mount a meaningful assault -- their mercenary groups are making some trivial gains here and there at great cost around Donbas, and they're still throwing missiles. Will they fold up once Ukraine pushes back in force? Hard to say, but maybe.
I guess I'm not understanding this whole weather thing. I mean, they're Russians, they invented winter. I guess we'll just have to wait until this million man army gets it's act together before we really see what Ukraine can do to push the orcs back int Ras Putin's lap.