Anything with a colour that goes with the weather, after all, it's the ambience of the environment. You want to make sure you match nature's colour pallete - because they already decided what colour fall will be this year!
But also dress warmly and a good idea for what style is in trend is: follow the general look if it's new because everyone's loving it; or go with its complete opposite if the style is getting old - then you will be ahead of the game!
T-shirts, jeans, vests and jackets. I'm preparing a gift for my dad: a size L "It's Not A Dad Bod It's A Father Picture" T-shirt and a pair of size XL jeans, I think my dad will really like it.