How do I adapt these ideas for a rainy day?
Start with the anchor piece, then pick one comfortable top and footwear that suit your plans. Treat colour and proportion as suggestions, not rules.
Do I need to buy new clothes?
No. Swap in a similar shape or fabric from your existing wardrobe. A simple tee, a useful layer and comfortable shoes can change how an outfit feels.
How should I adjust for the weather?
Use breathable layers in heat, a warmer removable layer when temperatures drop, and weather-resistant outerwear when rain or wind is forecast.