Not very hot.
Radiant Solutions Self-Regulating Heat Tape changes its heat output based on the temperatures of its surrounding environment. At any given point, depending on the temperatures outside, the cable could be a range of temperatures. However, its peak temperature is not very hot –typically between 95º-110º. Mainly because once the cable has heated the immediate area around it, the self-regulated aspect of the cable kicks in and prevents it from getting too warm.
This gives our Heat Tape a great advantage over the heat tape you can buy in ‘Big Box’ retailers, because it creates enough warmth to effectively do its job, but won’t do damage to surfaces that it touches. Additionally, our heat cable can be touching/overlapping when used. Heat Tape that is not self-regulating can not do this (they have explicit warnings in the directions not to do this for risk of fire).
We have even witnessed a coil of crappy big box heat tape starting a fire because it got plugged in when it was still coiled. (Yikes!)