Get SJTW for outdoor cords.

SJTW. That W means weather-resistant. SJT lacks it.

SJT is fine for occasional outdoor use if it stays dry and out of the sun, but the jacket isn’t designed for moisture or UV. Over time it cracks, absorbs water, and becomes a hazard.

SJTW is the same gauge and rating (300V, -40°C to +60°C typical) but with a jacket that handles rain, snow, and sun. It costs a few bucks more and lasts years longer.

Don’t save two dollars on the thing that carries electricity through your wet yard.