One may point out, as Lincoln did, that Scripture describes rain as falling equally on the just and the unjust.
Bad weather affected the Confederates as much as it did the Union forces.
Good point to make.
Underlying much of this, too, was teaching Union soldiers and citizens that the Confederate soldier's constant advertisement of himself as invincible would be less effective as propaganda the more the Union soldier fought him.
Unlike Burnside at Fredericksburg, Rosecrans at Stones River gave every bit as good as he got and kept the field.
That meant a lot in the ranks and back home.