I recall reading that temperatures 12 feet underground range between 55F and 65F (13-18C) year around. Found this chart [ https://www.builditsolar.com/Projects/

I recall reading that temperatures 12 feet underground range between 55F and 65F (13-18C) year around. Found this chart [ https://www.builditsolar.com/Projects/Cooling/time-lag-vs-depth.gif https://www.builditsolar.com/Projects/Cooling/time-lag-vs-de... ] which suggests that's true with a ground-temp range of 42F to 82F (6-27C). And then there's Coober Pedy, which enjoys a 104F temp swing each year. If/when things get dire, there's always underground (moving into new digs). Those cities in Turkey are getting easier to understand.