The solar wind and IMF data obtained by the Venus probe Mariner 5 (at a distance of 460 earth radii) and by the earthbound Explorer 34 satellite, on June 24, 25, and 26, 1967 were examined. It is demonstrated that the occurrence and intensity of magnetospheric substorms can be predicted about 1--3 hours prior to their onsets by monitoring the energy coupling function at a distance of a few hundred earth radii upstream of the solar wind. It appears that the '&egr; signal' propagates with different speeds, perhaps depending on the propagation time of disturbances which increase &egr;.