Of these, 81 were named, including a subtropical cyclone in the South Atlantic Ocean, by various weather agencies when they attained maximum sustained winds of 35 knots (65 km/h; 40 mph).

The deadliest and costliest storm of the year was Typhoon Morakot (Kiko), causing 789 fatalities and $6.2 billion worth of damages through its track in the Philippines, Japan, Taiwan, China, and the Korean Peninsula.

The accumulated cyclone energy (ACE) index for the 2009 (seven basins combined), as calculated by Colorado State University was 609.6 units.

These dates conventionally delimit the period of each year when most tropical cyclones develop in the Atlantic basin.

Activity began slightly early when Tropical Depression One developed on May 28, marking the third and last consecutive season with a pre-season storm.

Forming from the interaction of a tropical wave and an upper-level low, Claudette made landfall on the Florida Panhandle with maximum sustained winds of 45 miles per hour (72 km/h) before quickly dissipating over Alabama.

Overall, the season's activity was reflected with a very low cumulative accumulated cyclone energy (ACE) rating of only 53, the lowest since 1997.

Because of the low number of storms in the 2009 season, many of which were weak, short-lived, and/or very disorganized, the overall ACE value was ranked as below-average, totaling under 66.

These dates conventionally delimit the period of each year when most tropical cyclones form in the Eastern and Central Pacific basins.

Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed.

It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 miles per hour (63 km/h).

The season's activity, east of 140°W, was reflected with a near-average cumulative accumulated cyclone energy (ACE) rating of 100, roughly 94% of the 30-year median.

The North Indian Ocean featured a generally below average event in the annual cycle of tropical cyclone formation.

These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.

The Cyclone Fanele was the most intense of the month, reaching category 4 on the SSHWS scale, with a barometric pressure of 930 mbar.

The inactive 2009 Atlantic hurricane season ended when Hurricane Ida dissipated on November 10 (it transitioned to a Nor'easter just after, so it ended when "Nor'Ida" dissipated) Despite two tropical disturbances forming in August and September, the 2009–10 South-West Indian Ocean cyclone season actually didn't see a named tropical storm form until November 13.

Typhoon Nida was the most intense of the year, peaking at a pressure of 905 hPa, just ahead of Hurricane Rick of the previous month.