That's a great question! A scorching hot trash can is more than just an annoyance—it can speed up decomposition and make odors so much worse. Luckily, there are a few simple tricks you can try.
First, consider the placement. If possible, move your bin to a shaded spot, like under a tree, a patio overhang, or against a north-facing wall. Even a few extra hours of shade make a huge difference.
For a direct solution, you can create a reflective barrier. Lining the inside with aluminum foil or a reflective emergency blanket is surprisingly effective. It bounces the sun's rays right back out. You can also use a specialized insulated trash bag as a liner.
Improving airflow is key. If your lid is solid, you might drill a few small ventilation holes near the top of the can (not the lid, to keep rain out). This allows hot air to escape. Just be sure the holes are small enough to keep pests out.
A quick fix on extra-hot days is to simply hose down the outside of the can in the morning or early afternoon. The evaporation will help cool it temporarily.
Finally, make it a habit to put bagged trash in the can, never loose waste. This contains heat and odor. Taking the trash out for collection regularly, even if it's not completely full, also prevents heat from building up over days.
Start with strategic placement and a reflective liner—those two steps alone will likely solve most of your overheating problems.