At midday on July 16, a tropical depression formed. It acquired gale-force winds 12 hours later and was named Estelle. On July 18, it intensified into a hurricane. In an environment that favored an increase of the storm's winds, Estelle continued strengthening, and became the first major hurricane of the season on July 20. Estelle's forward motion increased to close to 20 knots. Estelle's path took it towards a potential landfall on the Big Island. Due to a shearing environment from a trough, Estelle weakened as it continued approaching Hawaii. A possible recurve never materialized, and the cyclone continued its path towards the Hawaiian Islands.