Enough to start a fire if cloth or paper comes in contact with it for a few minutes. My sister once set up a "reading room" in her closet when we were kids. The light she put in the the closet had no lampshade, and the exposed bulb ended up igniting her clothes in the middle of the night (she had left the light on). She woke up in a smokey room, ran and grabbed the fire exstinguisher and put the fire out herself. There was very lttle damage, but it scared her pretty good.