Disposable vapes look like one solid piece, but they're really a few parts working together. The battery powers the coil, the coil heats up, and the e-liquid saturates the wick. Airflow comes through the bottom or side, and the mouthpiece is where the vapor exits. When you're in cold weather, each part behaves a little differently. The battery doesn't like extreme cold (it can drain faster), the e-liquid gets thick, and the wick struggles to soak it up. That's why a vape that felt fine indoors can suddenly feel weak and airy outside.