Cold weather summer fashion

I live in a place where it never really gets warm; it can get up to 23-24C in peak summer but it's usually around 20C, and right now it's only around 13C and windy.

How can I style summer outfits to still feel/look summery but also keep warm?

I don't mind the look of a sweater over a sundress but they always feel so wintery and seem to clash with the lighter fabric of the dresses (or maybe it just feels that way because I'm sick of wearing thick sweaters all year round lol)