Resysta material will not swell or warp when the installation guidelines are followed. As every composite material it needs a little room to expand and contract.

Like with wood or composites it depends a lot on the color. Resysta is using heat reflective pigments to lower the temperature as much as possible. But this dark color like in the picture will get very warm. Resysta material has a very similar temperature like real wood when we compare the same color.