Is Tozeur or Douz too hot to visit around this time?

Hi guys, I'm currently travelling in Tunisia (in Kairouan at the moment). I'm going to Tataouine tomorrow for three days and then have no plan for another four days. I'm thinking if I should go to Douz or Tozeur to see some desert places, but I'm worried if it's too hot. I'm not even sure if there's any tour available in this weather?? If it's not really doable, I might just go up north again to Sousse..