My pick for round 4 is Neohealy's entry.
I think the colors speak more towards the richness of Summer, but more importantly, the fabric choice of cottons/linens/similar and lightness of the look (even despite multiple layers!) really identify the season. Seperately, you wouldn't think turquoise and a light pea greenish would work well together, but these seem to be just the right shades to be interesting while still complementary.
On a technical level, I'm most impressed by the outfits versatility. Each "look" stood alone, but the combined all-in-one works really well too. That there was a lot of thought put into positioning really shows. The third layer from the top, of turquoise is positioned very well, against the asymmetrical hemline of the second layer.
Other small details also add to the look without overwhelming it, like the lace edging, embroidery on the turquoise (even though it's pre-done) and the "jewels" in the center.