The summer heat is here and we remind our pilot friends to excercise extra caution accounting for density altitude effects - lower prop efficiency, decreased lift, and decreased power output from the engine.  Aicraft will not get off the ground, carry the load, or turn as well when high density altitude exists. What was fantastic conditions in early morn at 1000" MSL can turn to a density altitude of 4100 MSL in the heat of the day.  Here is an excellent calculator to help you determine your conditions.