If your hunt is the last week in Sept. The elk will be hot but also grouped up as the big bulls will be running herds. The full moon will have an impact. It gives the elk light to do what they need to do[rut] at the coolest temps possible. So they will but they rut at night anyway. The day time temps prior to this time frame will also have an impact on how much activity you will see during the day. The real trick with elk hunting is being able to adjust to what is happening daily. Your guide should know what to do in any case.