Atlantic hurricane seasonal changes

The 2024 hurricane season began with the earliest Category 5 hurricane ever recorded. In an unprecedented twist there was an eerily long and unexpected lull during the peak season, before ending with a flurry of activity in the Gulf. Next month, Charles Powell, from the University of Cambridge, and I will be sharing a retrospective of 2024 as part of the work that Inigo is funding under its InSPIRe programme.

The chart compares the timing of the first and last major hurricanes for the climatological periods 1980-2020, 1980–2000 and 2000–2020 and compares these to 2024. The vertical lines denote the temperature range between the first and last major hurricane and the horizontal line the mean temperature. From the climatological data we can see that there is a fairly well-defined start to the first major hurricane in the season, but that the end of the season appears to be extending, with the last major hurricane occurring later in the 2000–2020 period compared with the earlier 1980–2000 period. The first major hurricane of 2024, Beryl, is a remarkable outlier becoming a major hurricane on the 30^th of June. The last major hurricane of 2024, Rafael, reached  major hurricane status on the 6^th of November, which, while not unprecedented, is approximately two standard deviations from the long-term mean.

Our analysis shows that the average temperatures in the Atlantic main development region have increased between the early and later periods, 1980–2000 and 2000–2020, with 2024 being one of the hottest years on record. As global temperatures continue to rise due to climate change, warmer oceans are able to sustain major hurricanes earlier and later in the season potentially leading to extended hurricane seasons This could pose a challenge for the insurance sector, as amplified hurricane risk over a longer season increases the potential for catastrophic loss events.