Don't plug a space heater into a 16-gauge extension cord.

No. This is one of those things where the risk is real, not theoretical.

Space heaters draw a lot of current—typically 12 to 15 amps on high. A 16-gauge extension cord is only rated for about 10–13 amps depending on length. That means you’re already pushing it at best, and if the cord is long or old, you’re asking for heat buildup, melted insulation, and eventually a fire.

You might get away with it for a while. But “getting away with it” is not the same as safe. The cord gets warm, the resistance goes up, and that’s how things catch fire in the middle of the night.

If you absolutely must use an extension cord for a space heater, get a 12-gauge or thicker (lower number) cord that’s rated for at least 15 amps. Even then, keep it as short as possible and fully uncoiled. But honestly? Plug the heater directly into the wall. Extension cords are not where you save two bucks.