The already-catastrophic 2017 hurricane season shows no signs of letting up, with Tropical Storm Nate threatening to blast into the Gulf Coast this weekend, likely as a hurricane.

And we still have nearly two months to go — the season doesn't officially end until Nov. 30.

The ferocity of the Atlantic storm season isn't just in your imagination. Thanks primarily to monsters such as Harvey, Irma and Maria, it's one of the worst in years by various meteorological standards.

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For example: The number of hurricanes that have formed this year — eight so far — is about double the average to date, as is the energy generated by the storms.

In a statistic known as "Accumulated Cyclone Energy" (ACE), the number in 2017 (204) is the highest it's been since 2005, the year Hurricane Katrina hit, 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 hurricanes or tropical storms have lower values (Katia came in at 6.1).

The average Atlantic ACE to date is 86, Klotzbach said.

There have also been 46 "hurricane days" this year in the Atlantic, also more than double the average.

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.

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

Another stunning record set in 2017: For the first year in recorded hurricane history, which dates to 1851, three Category-4 hurricanes (Harvey, Irma and Maria) slammed into the United States and its territories the same year.

As for the reasons for the active season, one of the factors is likely a lack of dust blowing across the Atlantic from Africa, which tends to have a drying effect on developing storms, according to AccuWeather. The lack of an El Niño — and its shearing winds that can tear apart nascent storms — is also playing a role.

Warmer-than-normal ocean temperatures, possibly tied into man-made global warming, also fueled the storms' ferocity.

Costliest season ever?

These statistics don't necessarily gauge a hurricane season's impact on people and property, however.

Harvey killed 75 people, mostly in Texas, while Irma killed 87 people in the U.S. and its territories. The U.S. death toll from Maria now stands at 34 in Puerto Rico.

"There is no question that this is already going to be one of the costliest Atlantic hurricane seasons on record," said meteorologist Steve Bowen of global reinsurance firm Aon Benfield. "Regardless of where the final numbers settle, this season is one which will be remembered for a very long time."

He said that when event impacts from July through September are combined, "the third quarter of 2017 is expected to tally as one of the costliest quarters ever registered for natural disasters.”

Final cost estimates from this season won't be available until early next year, said Brady Philips, spokesman for the National Oceanic and Atmospheric Administration.

Blast from the past?

Yet, as bad as it's been, some of this season's intensity is really just a blast from the past.

Irma, for instance, was "reminiscent of the great hurricanes that unleashed their fury on Florida in the first seven decades of the 20th century ... and then for the most part disappeared," said Weather Channel meteorologist Bryan Norcross before the storm hit.

"Mother Nature’s hurricane-output cycle has its ups and downs," he added, "and a lull came along in the 1970s, 80s, and early 1990s — Hurricanes Frederic, Hugo and Andrew notwithstanding."

Overall, with eight hurricanes so far this year, 2017 is unlikely to touch 2005's all-time record of 15 hurricanes. However, 5 major (Category 3 or stronger) hurricanes have formed, almost as many the record-smashing 2005 season generated up to that point in the season.