Five meters down in the desert you're under 25 degrees year round. It's the average that matters for soil temps, not the peaks. You can approximate this by taking the average air temperature and defining the surface as the top five meters. Below the 10 meter mark the day/night cycle influence is pretty much negligible (but that would be more costly).

For instance:

https://www.researchgate.net/figure/Temperature-variation-of...