AbstractTaking advantage of the high spatial‐resolution and global coverage of Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager observations, we investigated the critical interplanetary factors in controlling the cusp auroral emission by dividing the midday auroras into the gap (weak emission) and non‐gap (intense emission) events. Although the cusp auroral intensity is essentially determined by a parameter related to the IMF (interplanetary magnetic field) direction, IMF magnitude (|By|), and solar wind speed (V), we found that the cusp aurora is statistically weak during the southward IMF but intense when the V and IMF |By| are greater. Further, we confirmed that even with V > 600 km/s, the intense‐aurora event still shows a minimum occurrence near the IMF |By| = 0. However, when the IMF |By| is greater, the V becomes less significant for the intense‐aurora occurrence. These results demonstrate that the IMF |By| is critical in controlling the cusp auroral intensity, most likely by producing an electric field which is given as .