How many calories are burned working in 120 plus degree heat?

As far as I know, close to the same as a more comfortable temperature. Your body has to work to circulate blood faster during intense physical activities and regulate a lower temperature, true, but if you're looking to burn more calories in a "gym workout" form, go for a cooler temperature. Your body will have to work much harder to maintain a higher temperature. Working in a hot climate will only dissipate water from your body. However, working out in a cooler temperature can be dangerous for your muscles (your muscles work like a rubber band). Typically, you want to go for the ideal conditions. Anything extreme can be harmful such as temperatures exceeding 95 degrees or below 65. Your body may begin to shut down to preserve vital conditions otherwise.