1. RF energy level: The device generally has different gears. The higher the energy, the more obvious the warm feeling. 2. Skin contact time: Long-term use will gradually increase the skin temperature 3. Skin condition: If the skin is dry, it may feel warmer; if gel or skin care products are applied, the warm feeling may be milder. 4. Ambient temperature: The temperature of the device may be different in warm or cold environments. Generally speaking, the temperature of RF beauty devices is controlled between 38-42°C, which is a safe and effective temperature range. If you are worried about the temperature being too high or too low, you can test different energy gears and use skin care products to adjust the experience.