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.

6.1 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 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.

6.1.1 Water Depth

Note that the water level data at Pellicer Creek only includes data from 2021–2025, 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.

6.2 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
2025-07-20	6.75
2025-07-21	3.00
2025-07-22	2.75
2025-07-27	8.00
2025-07-28	9.25
2025-07-29	7.25
2025-07-30	4.25
2025-07-31	5.75
2025-08-01	4.75
2025-08-02	4.25
2025-08-14	2.75
2025-08-16	5.00
2025-08-21	4.00

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.