In the region where I live summers are relatively hot (up to 35°C or 95°F) and sunny. Some of my plants grow in dark plastic pots, which can get pretty warm. When I water them, the water and the soil get very warm as well.
So far no plant was boiled alive, but I'm really afraid of this scenario. Would replacing those plastic pots with clay pots help to keep the soil a bit cooler, or does it make no/very little difference?