Record warm water temperatures in the Atlantic Ocean and atmospheric conditions over the Western Hemisphere have prompted new warnings of increased hurricane activity that could threaten communities along the Atlantic and Gulf coasts.

“The main climate factors expected to influence the 2023 Atlantic hurricane activity are the ongoing El Niño and the warm phase of the Atlantic Multi-Decadal Oscillation,” said Matthew Rosencrans, lead hurricane season forecaster with the National Oceanic and Atmospheric Administration.

Earlier this year, NOAA’s Climate Prediction Center forecast a “near normal” season with 12 to 17 named storms, including five to nine reaching hurricane strength and up to four becoming major hurricanes with sustained wind speeds topping 111 mph. The updated forecast, released Aug. 10, predicts 14 to 21 named storms, including six to 11 that could reach hurricane strength with two to five of those becoming major hurricanes.

Last year, the Atlantic hurricane season produced 14 named storms, including eight that reached hurricane strength and two that developed into major hurricanes.

This year’s Atlantic hurricane season got off to an active start, with five tropical storms, including one that reached hurricane strength. But El Niño effects on the atmosphere and Saharan dust from Africa have otherwise suppressed tropical storm formation.

The updated NOAA forecast is now calling for as many as 16 additional storms before the season concludes in autumn. The six-month Atlantic hurricane season began June 1 and continues through Nov. 30.

Researchers with Colorado State University’s Tropical Weather and Climate Research team issued a similar seasonal update earlier this month. Their final seasonal forecast now calls for 18 named storms, with nine reaching hurricane strength and four developing into major hurricanes.

CSU meteorologists cited data from seven seasons dating to 1951 with similar conditions. Four of those seasons, 2004, 2005, 2006 and 2012, included the devastating storms Ivan, Katrina, Rita and Sandy—all names retired due to the extent of devastation and loss of life they caused.

“Our analog seasons exhibited a wide range of outcomes, from below-normal seasons to hyperactive seasons,” said Phil Klotzbach, a research scientist in CSU’s Department of Atmospheric Science and lead author of the report. “This highlights the large uncertainty that exists with this outlook.”

Record warm sea surface temperatures in the tropical and subtropical Atlantic and the possibility of El Niño’s effects on wind patterns are seen as contributing factors to a potentially active period ahead, Klotzbach said.