The Voyager data show a decrease in temperature in the inner heliosphere, an increase in temperature from 30--50 AU, a decrease from 50--63 AU, followed by another increase from 63--68 AU. Models of pickup proton heating predict a monotonic temperature rise beyond about 30 AU but do not account for the smaller scale (few AU) temperature variations. At 1 AU, the solar wind temperature is a strong function of the solar wind speed. We find that incorporating a temperature dependence on speed into the pickup proton heating results can reproduce much of the smaller-scale temperature variation observed out to 68 AU. The same speed-temperature dependence provides good fits to data from both the outer heliosphere and from near Earth. Since a large fraction of the proton energy results from heating, this work implies that the heating rate is a function of the speed.