The energy equations for ions and electrons moving in a neutral gas have been used to predict the changes in electron ( T e ) and ion ( T i ) temperatures in ionospheric sporadic- E ( E s ) layers formed according to the wind shear theory. It is predicted that within such an E s layer T e has a minimum and that T e is greatest in regions of low electron density; overall variations in T e of about 70°K are expected near an altitude of 115 km, these variations increasing with altitude and electron density. Vertical electric fields produced by gradients in electron density might produce additional, observable, double hump variations in T e at night, at altitudes of about 130 km.