The 1984 Atlantic hurricane season was the most active since 1971, though the season was below average in hurricanes and major hurricanes. It officially began on June 1, 1984, and lasted until November 30, 1984. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The 1984 season was an active one in terms of named storms, but most of them were weak and stayed at sea. Most of the cyclones tracked through the northwest subtropical Atlantic west of the 50th meridian to near the Eastern coast of the United States between mid-August and early October. The most damaging storm was Hurricane Klaus, which caused $152 million (1984 dollars) in damage in Puerto Rico. Hurricane Diana was the first hurricane to strike a nuclear power plant without incident; it was also the first major hurricane to strike the U.S. East Coast in nearly 20 years. Also of note was Hurricane Lili, which lasted well after the official end of the season. It was downgraded from a named storm on December 24. Damage overall from the tropical cyclones in 1984 totaled $228.7 million. Unusually, no hurricanes developed from tropical waves in 1984, which usually are the source of the strongest storms in an Atlantic hurricane season.

The 1984 Pacific hurricane season featured numerous tropical cyclones, several of which were impactful to land. It was a busy hurricane season with 21 named storms, 13 hurricanes, and 7 major hurricanes, the latter of which are Category 3 or stronger cyclones on the Saffir–Simpson scale. This activity was unusual given the presence of a La Niña, which typically suppresses Central and East Pacific tropical cyclone activity, and only average sea surface temperatures. Seasonal activity began on May 17 and ended on November 8. This lies within the confines of a traditional hurricane season which begins on May 15 in the East Pacific and June 1 in the Central Pacific, and ends on November 30 in both basins. These dates conventionally delimit the period during each year when most tropical cyclones form.