Why is my vapour too hot?
If your vapor is burning your lips, start by opening your airflow more to let in extra fresh air. You can also lower your mod's wattage or opt for a longer drip tip, which gives the vapor time to cool down before reaching your mouth. Finally, check that your e-liquid isn't too thin for your coil, as a lack of liquid can cause the heating element to run excessively hot.
Technically, the temperature depends on the ratio between the heat produced by the coil and the volume of air passing through it. Too little airflow combined with high power turns your atomizer into a tiny oven. For your safety, always stay within the power range recommended by the manufacturer. Vapor that is too hot can not only distort your flavors but also irritate your airways over time.