I live in an area where I can go from bone-chilling cold in the winter, to 100+F in the summer, so I had to find solutions for all of the above fairly early on.

I conceal carry when I have to, these days, but most of the time I open carry with a lvl 3 retention holster from Safariland. It's a gun-loving state, and I like to help keep the sight of someone carrying a sidearm considered normal around here.

One of my favorite options for lighter clothing, concealed, and on-body is the Crossbreed Modular Belly-Band. Takes all the weight off your clothing, so you can literally wear whatever you want, with or without a belt.