From the air, the devastation Hurricane Maria brought to Puerto Rico appears to be catastrophic.

Farewell, September. Don’t let the door hit you on the way out.

By some measurements, September marked the single worst month for Atlantic hurricanes ever recorded.

In a statistic known as “Accumulated Cyclone Energy” (ACE), Hurricanes Irma, Katia, Jose, Lee and Maria generated the largest amount of energy for any month on record, according to Colorado State University meteorologist Phil Klotzbach.

ACE is calculated by adding each tropical storm or hurricane’s wind speed through its life cycle. Long-lived, intense hurricanes have a high count (Irma’s ACE measured 67.5), while short-lived, weak tropical storms have a lower values (Katia came in at 6.1), according to 

Both Irma and Maria soared to Category 5 strength, the top of the Saffir-Simpson scale of hurricane intensity. Irma’s landfall on Barbuda and Maria’s landfall on Dominica makes 2017 only the second season on record to feature two hurricanes that hit at Category 5 strength.

The Atlantic Basin, which includes the Gulf of Mexico and the Caribbean Sea, also generated 35 “hurricane days” in September, the most in the Atlantic of any month on record, Klotzbach added.

A “hurricane day” is tallied each time a hurricane spins for 24 hours somewhere in the Atlantic, meaning there can be multiple “hurricane days” in a single 24-hour period. 

Costliest season ever?

These statistics don’t necessarily gauge a hurricane…