Don't daisy-chain extension cords for a space heater.

No. That’s a fire waiting to happen.

Two 100-foot cords means 200 feet of total wire. Voltage drop over that length means the heater will draw more current to compensate, which can overheat the cords. Even if each cord is rated for 15 amps (which should handle 1500W at 120V), the combined resistance and potential for poor connections at the daisy-chain point adds risk.

Extension cords aren’t designed for continuous high-wattage loads like space heaters. Running one heater on a single heavy-duty 100-foot cord is already pushing it. Stacking two multiplies the danger: heat buildup, melting insulation, and a real chance of starting a fire.

If you absolutely must power a space heater that far from an outlet, get a single 200-foot, 12-gauge or thicker cord rated for outdoor use. Or better, move the heater closer. This is not where you save six bucks.