NOAA Updates Its 'Average' Hurricane Season to Call for More Storms

Hurricanes Harvey, Irma, and Maria in 2017.
Hurricanes Harvey, Irma, and Maria in 2017.
Image: NASA

On Friday, the National Oceanic and Atmospheric Administration released its new “average” estimate for Atlantic hurricane season. If trends follow the period from 1991 to 2020, the Atlantic region should expect 14 named storms, seven hurricanes, and three major hurricanes. This isn’t the annual outlook; it just slightly moves the bar for what the average could look like this decade.


NOAA computes new averages every decade for hurricanes as well as other climate measurements from heat to rainfall. That allows for them to make forecasts that accurately reflect comparatively recent conditions from a climate perspective. The new average for hurricane season includes two more named storms and one more hurricane compared to the previous average of 1981 to 2010.

The agency notes that the higher average could be due to a mix of ocean warming and more sophisticated satellites and monitoring systems. It’s likely that the climate crisis is involved; research shows climate change increased the odds of 2017's hurricane season that spawned a spate of monster storms, including Harvey, Irma, and Maria. Climate change is also influencing the damage from individual storms; the record rainfall from Harvey, for example, was made more likely.

Yet last month, NOAA published a study reviewing Atlantic basin hurricanes on a 100-year timeline and found insubstantial evidence that greenhouse gas-induced warming will necessarily lead to a long-term increase in hurricanes. But it did confirm that carbon-linked warming is intensifying hurricanes globally, not to mention that rising sea levels and higher rainfall drastically worsen floods. The long and short of it is it’s a complicated topic researchers are still working to understand.

The increased activity in the basin was particularly acute last year when so many named storms (31, a record high) formed in the basin, the World Meteorological Organization ran all the way through the alphabet and into Greek letters. The hellish season broke records for the latest Category 5 storm and most U.S. landfalls, left hundreds dead, and a total of six storms in the U.S. wreaked more than $1 billion in damage. it continued a disturbing trend in recent years, particularly for Category 5 storms, which we’ve seen hit the basin five years and counting. That represents the longest-ever streak on record.

While NOAA hasn’t issued a forecast for this coming hurricane season, other forecasters are putting theirs out with an ominous message. This year already looks to be a little worse than “average;” Colorado State University climate researchers released an estimate on Thursday calling for 17 named storms, 8 hurricanes, and 4 major hurricanes. While the group also put out estimates for landfall odds in a given location, it’s important to remember that it only takes on storm making landfall to do serious damage.

The NOAA plans to release this year’s outlook in late May. The agency will also begin issuing warnings earlier than the official June 1 start date, reflecting the fact that all aspects of hurricane season are in flux.


Staff reporter, Gizmodo. wkimball @ gizmodo


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Further explanation is a good thing. For me at least. NOAA has an explainer on this 30 year normal thing aptly titled:

“Understanding Climate Normals”

 (google NOAA + title below for link)

And expressly mentioning:

It’s important to understand that NOAA’s Climate Normals are not simple 30-year averages of weather observations. NOAA’s climate scientists don’t calculate Normals by adding up 30 years’ worth of weather data and dividing by 30.