Perhaps this doesn't really count as an outfit but when it gets to a certain temperature, you find yourself looking for ways to where as little as possible whilst still remaining dressed.
I had the kids today, so I dug out my shorts from a plastic bag stashed on top of my wardrobe; they make an appearance maybe once a year. They're so practical and comfy that I think of this as a shame and so pull them back out at the first opportunity. The bikini top I bought in a rather optimistic mood during a warm spell in March. It's sat unusable since then, my winter coats have had more use. Acknowledging that perhaps this might be the only chance I have of wearing it - and look how pretty it is, it deserves to be worn - I braved out my tummy fears and threw a cropped white Tee over the top for most of the day.
At the beach, the sun hit full force, so I ended up soaking in some rays in one of my only pieces of swimwear. I can assure you, there was some major sucking in going on, even if we were mostly alone. Habit, I think. Nothing improves your posture more than showing your tummy!