6  Environmental Drivers

This section includes drivers of environmental patterns such as significant weather events (e.g., tropical cyclones, Nor’easters, large rainfall events), anomalies, and other local events with impact.

6.2 Nor’easters

Typically, a Nor’easter is a storm along the East Coast of the United States with predominating winds from the northeast. These storms can last anywhere from a single day (24 hours) to several days or weeks. Callahan, Leathers, and Callahan (2022) found that these events can produce surges just as severe as tropical cyclone events and occur more frequently. These events are often in the news associated with blizzards in the New England area of the US; however, their impacts to Northeast Florida, including higher water levels, heavy prevailing winds, precipitation, and reduced tidal exchange, can be significant.

Table 6.1: Extreme storms that affected the GTMNERR from September 2002-June 2025. Asterisks (*) represent storms listed in NOAA’s Historic Hurricane Tracker as coming within 60 kilometers of the GTMNERR. Cardinal directions for wind were converted using a 16-point meteorological compass found at https://planetcalc.com/3590/. H = Hurricane, TS = Tropical Storm.
Year Month/Day  Name Total Rainfall (mm) Ave Wind Speed (m/s) Max Wind Speed (m/s) Ave Wind Direction (Degrees) Cardinal Direction
2004 08/13 – 08/15 H Charley* 114.8 2.2 25.9 176.4 S
2004 09/04 – 09/08 H Frances 203.2 7.4 28.1 123.4 ESE
2004 09/19 – 09/21 H Ivan 35.1 7.2 14.4 46.5 NE
2004 09/26 H Jeanne 57.5 13.6 24.4 91.3 E
2005 09/05 – 09/09 H Ophelia 122.6 7.5 16.0 76.6 ENE
2005 10/04 – 10/06 TS Tammy* 40.1 4.2 18.5 121.2 ESE
2005 10/24 – 10/25 H Wilma 45.4 3.5 15.4 288.9 WNW
2006 08/24 – 09/04 H Ernesto 78.0 2.0 9.6 185.9 S
2007 05/31 – 06/05 TS Barry 88.6 3.2 14.7 176.8 S
2008 08/20 – 08/25 TS Fay* 200.9 5.9 20.6 117.3 ESE
2012 05/27 – 05/29 TS Beryl* 86.2 3.5 15.3 215.4 SW
2012 06/23 – 06/27 TS Debby* 141.0 3.4 14.6 172.1 S
2016 06/05 – 06/07 TS Colin 127.3 2.2 11.7 189.5 S
2016 08/28 – 09/06 H Hermine 66.0 2.7 12.8 130.8 SE
2016 09/14 – 09/19 TS Julia* 26.9 2.3 8.6 140.3 SE
2016 09/28 – 10/09 H Matthew* 193.2 3.6 28.9 142.6 SE
2017 09/10 – 09/12 H Irma 222.3 6.6 29.1 149.2 SSE
2019 09/03 – 09/05 H Dorian 83.8 5.1 19.1 178.0 S
2020 11/12 H. Eta* 12.4 3.7 13.4 211.0 SSW
2022 09/28 – 10/01 H Ian 238.0 5.6 21.5 182.1 S
2022 11/08 – 11/11 H Nicole 100.4 6.7 18.8 86.0 E
2023 08/29 – 08/30 H Idalia 17.7 3.1 16.6 176.8 S
2024 08/04 – 08/06 H Debby 35.7 3.8 13.7 174.2 S
2024 09/25 – 09/26 H Helene 24.9 4.9 17.4 142.0 SE
2024 10/09 – 10/10 H Milton 185.7 8.2 26.1 85.0 E
Figure 6.1: Daily median wind speeds observed in 2025 at the Pellicer Creek weather station. Winds from the north-northeast and east-northeast directions are identified with color, all other values are gray.
(a) Monthly wind speeds
Figure 6.2: Monthly wind speed and direction from the Pellicer Creek weather station for January - June 2025.

6.3 King Tides

“King Tides” are the highest predicted tides of the year and in Northeast Florida, these typically occur during the fall and winter months. For the city of St. Augustine, these events often bring nuisance flooding in coastal and low-lying areas. For the estuary, this typically also means reduced tidal exchange, a lack of low tide events, and more and prolonged flooding in the intertidal wetlands. The city reports these events on their website.

Predicted King Tide events in 2025 are:

  • January 11th-14th
  • September 9th-14th

6.3.1 Water Depth

Note that the water level data at Pellicer Creek only includes data from 2021–2024, which is due to this station switching from reporting depth to reporting level (NAVD88) in 2021 (Figure 6.3 (d)).

(a) Pine Island
(b) San Sebastian
(c) Fort Matanzas
(d) Pellicer Creek
Figure 6.3: Historical daily range of water depth at each SWMP water quality station with current year daily average overlaid in blue.

6.4 Temperature anomalies

Extreme temperatures, both high and low, have drastic impacts on environmental processes. For black mangroves (Avicennia germinans), temperatures under -4°C have been found to reduce mangrove cover (Cavanaugh et al. 2013). Extreme high temperatures are often health risks as they result in many heat-related illnesses.

No freeze events were recorded this year.

Figure 6.4: Monthly temperature anomalies at GTMNERR Pellicer Creek weather station from 2002-2025
Figure 6.5: Comparison of average dew point and air temperature with total monthly precipitation for the month of June. This year is indicated in red.
Figure 6.6: Hourly averaged heat index values recorded at the Pellicer Creek weather station in 2025 with values in excess of 113 degrees colored in red.
Table 6.2: Date and duration of temperatures over 90 degrees fahrenheit for greater than 2 hours at the Pellicer Creek weather station
Date Duration (hrs)
2025-05-16 4.75
2025-05-17 6.50
2025-05-21 6.25
2025-06-08 3.00
Callahan, John A, Daniel J Leathers, and Christina L Callahan. 2022. “Comparison of Extreme Coastal Flooding Events Between Tropical and Midlatitude Weather Systems in the Delaware and Chesapeake Bays for 19802019.” JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY 61.
Cavanaugh, Kyle C., James R. Kellner, Alexander J. Forde, Daniel S. Gruner, John D. Parker, Wilfrid Rodriguez, and Ilka C. Feller. 2013. “Poleward Expansion of Mangroves Is a Threshold Response to Decreased Frequency of Extreme Cold Events.” Proceedings of the National Academy of Sciences 111 (2): 723–27. https://doi.org/10.1073/pnas.1315800111.