Using ESRO 4 measurements and interplanetary medium data compiled by King (1977), the direct correlation between perturbations of the upper atmospheric temperature in the polar region and changes in the solar wind properties was investigated. Here it was necessary to take the sluggish response of the upper atmosphere into account. Of the four solar wind parameters tested, the ϵ parameter (Perreault and Akasofu, 1978) yielded the highest correlation coefficients (≥0.7). It is suggested that this (or a similar) parameter should eventually replace geomagnetic indices in modeling atmospheric perturbation effects. Changes of the regression line coefficients with local time and season were observed but could not be analyzed in detail.