My go-to for the no melt in hot weather makeup is Temptu Airbrush- it is a little bit of an investment but if you live in that sort of climate it is well worth it! It is used on a lot of celebrities when they have to perform and sweat and need something to last.
If not that, I say try Hourglass Veil Primer with almost any foundation. It seriously holds your foundation on so well and it makes it water-resistant.
There is also a new 15-hour wear foundation by Smashbox that is amazing called Studio Skin.