How hot can a Hot Spring hot tub get?

Up to 104°F (40°C) is the federal maximum temperature a hot tub can heat to.

Generally speaking the optimal hot tub temperature is 100°F (36°C) to 104°F (40°C).  This temperature is not only comfortable to bath in but it is also what medical professionals consider safe for healthy adults.  Use lower temperatures for younger children and extended enjoyment of the hot tub.  Always consult your doctor or child's pediatrician to see if you are healthy enough to use a hot tub.