Because of its tilted axis the Earth is heated unevenly. Its surface is also rough and irregular. All of this creates temperature and pressure differences which cause winds–especially upper air winds. Temperature contrasts are stronger in the cold months and that drives everything!
When the upper winds blow strong weather systems move quickly. That’s what we’re leaving.
From now until the fall weather systems will move slower. Fronts and air masses will be a little more spongily defined.
There are certainly forecasting differences. Timing becomes tougher. On convective days very small, but nearby areas will sometimes have radically different weather.
Of course you’re less critical because the forecast usually has less impact this time of year. I appreciate that.