Rising sea levels increase storm surge damage
Of the six tide gauges on Florida's west coast with long-term records, Helen set all-time high water records at three of them (Cedar Island, Clearwater Beach and St. Petersburg) – in all three cases at midnight Thursday night Two other hurricanes (Fort Myers and Naples) ranked second or third before or after Hurricane Ian in 2022 and Hurricane Irma in 2017. Rising sea levels make these records easier to set. Since 1947, sea level has risen approximately 3.09 mm per year at the St. Petersburg, Florida tide gauge, which, if extrapolated to 100 years, works out to approximately 0.3 m (1.0 ft) (Figure 1). A large portion of sea level rise is the result of human-caused global warming; global sea levels are projected to rise approximately 7.5 inches (0.19 meters) since 1900. Much of this rise is caused by melting glaciers and thermal expansion of water. Sea level rise has accelerated along Florida's coast over the past decade, with sea levels rising in St. Petersburg at about 7 millimeters per year (2.3 feet per century). Changes in ocean circulation and wind patterns, as well as climate change, are potential influencing factors thought to be responsible for the acceleration.
Six of the top 10 water levels in St. Petersburg since 1947 (highlighted in bold) occurred after 2012. Set new water level. Here are the top ten water levels in St. Petersburg since 1947, calculated by the mean higher water level (MHHW) measured above:
- 6.31 feet, September 27, 2024, Hurricane Helen
- 4 feet, August 31, 1985, Hurricane Elena
- 3.8 feet, August 30, 2023, Hurricane Idalia
- 3.58 feet, Tropical Storm Josephine, October 8, 1996
- 3.52 feet, June 18, 1982, Subtropical Storm One
- 3.37 feet, Tropical Storm Eta, November 12, 2020
- 3.16 feet, December 17, 2023, winter storm
- 2.74 feet, September 6, 2004, Hurricane Francis
- 2.91 feet, March 13, 1993, Storm of the Century
- 2.74 feet June 25, 2012 Tropical Storm Debbie
Here are the seven highest water levels (above mean higher water, or MHHW) on Cedar Island since 1914, again with records set since 2012 (shown in bold):
1) 9.3 feet, September 27, 2024, Hurricane Helen
2) 6.84 feet, August 30, 2023, Hurricane Idalia
3) 5.98 feet, September 2, 2016, Hurricane Hermine
4) 5.41 feet, August 31, 1985, Hurricane Elena
5) 5.15 feet, Tropical Storm Josephine, October 8, 1996
6) 5.13 feet, March 13, 1993, storm of the century
7) 4.66 feet August 5, 2024, Hurricane Debbie
Here are the first six water levels from the Clearwater Beach tide gauge on the Gulf side of St. Petersburg, where records date back to 1973:
1) 6.67 feet, September 26, 2024, Hurricane Helen
2) 4.02 feet, March 13, 1993, Storm of the Century
3) 3.58 feet, August 30, 2023, Hurricane Idalia
4) 3.32 feet, January 3, 1999, winter storm
5) 3.17 feet, August 31, 1985, Hurricane Elena
6) 2.91 feet, October 8, 1996, Tropical Storm Josephine
Here are the seven highest water levels in Naples since 1965 (the above are higher water levels, or MHHW):
1) 6.18 feet, September 28, 2022, Hurricane Ian (gauge failed before peak water level was recorded)
2) 4.02 feet, September 10, 2017, Hurricane Irma
3) 4.01 feet, September 26, 2024, Hurricane Helen
4) 3.11 feet, August 4, 2024, Hurricane Debbie (data from the new North Naples Bay Station)
5) 3.11 feet, December 22, 1972, winter storm
6) 3.08 feet, January 17, 2016, winter storm
7) 3.02 feet, September 28, 2023, Hurricane Idalia
Helene brought the second-highest water ever recorded to Fort Myers, Florida, where accurate records date back to 1965. ):
1) 7.26 feet, September 28, 2022, Hurricane Ian
2) 5.12 feet, September 27, 2024, Hurricane Helen
3) 3.41 feet, Tropical Storm Keith, November 23, 1988
4) 3.31 feet, September 14, 2001, Hurricane Gabriel
5) 3.30 feet, June 18, 1982, unnamed subtropical storm
6) 3.27 feet, August 4, 2024, Hurricane Debbie
7) 3.2 feet, August 30, 2023, Hurricane Idalia
Note that there were multiple reports of 8 to 12 feet of flooding in the Naples area and 7 to 11 feet of flooding in the Fort Myers area as a result of Hurricane Donna in 1960.
