At what temperature can a person see his breath?

When you breath out, you always breath out water vapor along with air. However, you can't usually see the water vapor because the water molecules are not close enough to form individual droplets. Individual droplets can be seen at the dewpoint.The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point is equal to the current temperature.Cool air can hold less moisture, which is why dew forms on the ground overnight, when the air cools.Back to your question:If the air has a higher humidity, you'll be able to see your breath at a higher temperature.If the air has low humidity, it will take a cooler temperature to be able to see your breath.This is why you can see your breath in the winter much more easily than in the summer.