Where North American Waters Are Warming Most Quickly

While the likely formation of an El Niño phase could balance out the danger, high ocean temperatures in the Atlantic have experts worried that the 2023 hurricane season could be more active than average. Favorable conditions for El Niño are present since the La Niña phenomenon ended in March, but conditions of the El Niño-Southern Oscillation are currently still classified as neutral.

Data from the National Oceanic and Atmospheric Administration shows that out of all off-coast regions the agency monitors, temperatures in the zones relevant for hurricane formation - like the MDR and Caribbean islands - have diverged most from their 20th century average recently. In 2022 as a whole, they were 0.64°C (1.15°F) and 0.69°C (1.24°F) higher than that average, respectively. In April 2023, the latest month available with NOAA, they reached divergences of +0.78 and +0.85°C - above the +0.40 to +0.66°C April diversions of 2021 and 2022. In April of 2020, temperature divergences in these regions had reached even higher, to +0.91 and +1.13°C. The year had been the most active for Atlantic hurricanes since 2005, but also was the first year of the most recent La Niña episode, which favors Atlantic hurricane formation.

The La Niña phenomenon shifts colder temperatures and stronger trade winds to the Pacific, therefore exposing the Atlantic to warmer and less linear wind pattern more favorable for hurricane formation, as higher temperatures cause more evaporation and less linear winds allow for circular wind motions. If an El Niño phase were to start this year, it would shift cooler and windier conditions over to the Atlantic. However, ocean temperatures in the Central Atlantic band and the Caribbean that are rising as a general result of climate change would still have the power to strengthen hurricanes this season.

The following chart uses polynomial smoothing, which calculates trends taking into account gains and losses of fluctuating data over time.