It ended early however, with no tropical storms forming after October 6—a rare occurrence caused partly by El Niño conditions. The most intense hurricane of the season was Hurricane Isidore with a minimum central pressure of 934 mbar, although Hurricane Lili attained higher winds and peaked at Category 4 whereas Isidore only reached Category 3. The season's low activity is reflected in the low cumulative accumulated cyclone energy (ACE) rating of 67.[1] ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so low number reflects the small number of strong storms and preponderance of tropical storms.