September 2021 Tropical Cyclones Report

Summary

The Atlantic hurricane season remained active in September with 10 active named storms, including the remnants of Hurricane Ida. This count tied 2010 and 2020 for the most active storms in a September on record. Fortunately, most of the storms were weak or short-lived. The two exceptions were Major Hurricanes Larry and Sam. which were long-lived but remained out to sea with minimal impacts. The most impactful Atlantic storm in September was probably Hurricane Nicholas, which produced heavy rainfall over portions of the Gulf Coast that had already been drenched by Ida just two weeks earlier.

The three hurricanes and two major hurricanes in the Atlantic during September are both near their long-term averages. The accumulated cyclone energy (ACE: an integrated metric of the strength, frequency, and duration of tropical storms) is about one-third above normal due to the contributions from the two long-lived major hurricanes, Larry and Sam. The Atlantic hurricane season through September has had 20 named storms, which trails only the 23 that occurred through this point in 2020. The numbers of hurricanes, major hurricanes, and ACE are all above normal but well behind record levels.

The East Pacific only had one named storm in September, Hurricane Olaf. This ties 2010 and 2011 as the fewest September storms in the East Pacific since 1981. The East Pacific season through September remains near normal for the number of named storms but below normal for most other metrics.

The West Pacific had four named storms, including two Category-5 Major Typhoons, Chanthu and Mindulle. Chanthu caused heavy rain, flooding, and landslides as it passed near Luzon in the Philippines, but Mindulle remained farther out to sea with minimal impacts. The four named storms and two typhoons in September are both below normal, but the two major typhoons and the ACE are both near normal. The West Pacific activity January-September remains below normal by most metrics, except for the ACE, which is near normal.

Globally, there were 16 named storms in September, which is near normal. The four major tropical cyclones and the ACE are also near normal, but the six tropical cyclones were below normal. There have been 75 named storms globally in 2021 through September, which is tied for the fifth most since 1981. However, the 29 tropical cyclones and 14 major tropical cyclones are both below normal. The global ACE for 2021 is near normal through September.

North Atlantic

September 2021 North Atlantic Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Larry	3	September 1Sep 1-11	125 mph	955 mb
Mindy	TS	September 8Sep 8-9	45 mph	1004 mb
Nicholas	1	September 12Sep 12-14	75 mph	989 mb
Odette	TS	September 17Sep 17-18	45 mph	1001 mb
Peter	TS	September 19Sep 19-21	50 mph	1005 mb
Rose	TS	September 19Sep 19-22	50 mph	1004 mb
Sam	4	September 23-October 5Sep 23-Oct 5	155 mph	929 mb
Teresa	TS	September 24Sep 24-25	45 mph	1008 mb
Victor	TS	September 29-October 2Sep 29-Oct 2	65 mph†	997 mb†
†Value occurred in October

North Atlantic Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1851-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	10	5.5	1st (tied with 2 other Septembers)	10 (2010, 2020, 2021)
Hurricane Winds ≥ 74 mph (64 kts)	3	3.3	22nd (tied with 3 other Septembers)	6 (1933, 1998)
Major Hurricane Winds ≥ 111 mph (96 kts)	2	1.6	7th (tied with 10 other Septembers)	4 (5 Septembers)
Accumulated Cyclone Energy ACE×10⁴ kt²	78.0	57.9	10th	174.1 (2017)

North Atlantic Tropical Cyclone Season Counts January-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1851-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	20	11.0	2nd	23 (2020)
Hurricane Winds ≥ 74 mph (64 kts)	7	5.3	7th (tied with 5 other seasons)	10 (1893, 2005)
Major Hurricane Winds ≥ 111 mph (96 kts)	4	2.3	6th (tied with 1 other season)	6 (2004)
Accumulated Cyclone Energy ACE×10⁴ kt²	120.6	94.3	12th	224.4 (1933)

East Pacific

September 2021 East Pacific Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Olaf	1	September 8Sep 8-11	90 mph	977 mb

East Pacific Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1949-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	1	4.4	39th (tied with 2 other Septembers)	8 (1966, 1994, 2015)
Hurricane Winds ≥ 74 mph (64 kts)	1	2.5	32nd (tied with 6 other Septembers)	6 (1992)
Major Hurricane Winds ≥ 111 mph (96 kts)	0	1.2	30th (tied with 11 other Septembers)	3 (6 Septembers)
Accumulated Cyclone Energy ACE×10⁴ kt²	3.5	31.5	39th	112.1 (1992)

East Pacific Tropical Cyclone Season Counts January-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1949-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	16	14.0	14th (tied with 4 other seasons)	22 (1992)
Hurricane Winds ≥ 74 mph (64 kts)	6	7.5	27th (tied with 8 other seasons)	14 (1990, 1992)
Major Hurricane Winds ≥ 111 mph (96 kts)	2	3.9	28th (tied with 8 other seasons)	9 (1993)
Accumulated Cyclone Energy ACE×10⁴ kt²	82.7	111.8	31st	256.8 (1992)

West Pacific

September 2021 West Pacific Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Conson	TS	September 6Sep 6-11	70 mph	989 mb
Chanthu	5	September 6Sep 6-17	170 mph	908 mb
Mindulle	5	September 23-October 2Sep 23-Oct 2	165 mph	908 mb
Not_Named	TS	September 23Sep 23	40 mph	1001 mb

West Pacific Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1945-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	4	6.1	34th (tied with 4 other Septembers)	11 (1994)
Typhoon Winds ≥ 74 mph (64 kts)	2	4.0	35th (tied with 6 other Septembers)	7 (1956, 1996)
Major Typhoon Winds ≥ 111 mph (96 kts)	2	2.5	17th (tied with 14 other Septembers)	5 (1957, 1968, 1987)
Accumulated Cyclone Energy ACE×10⁴ kt²	74.0	66.6	15th	139.3 (1996)

West Pacific Tropical Cyclone Season Counts January-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1945-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	17	19.3	30th (tied with 1 other season)	29 (1965, 1971, 2018)
Typhoon Winds ≥ 74 mph (64 kts)	6	11.5	39th (tied with 2 other seasons)	20 (1971)
Major Typhoon Winds ≥ 111 mph (96 kts)	3	6.3	35th (tied with 4 other seasons)	13 (1965)
Accumulated Cyclone Energy ACE×10⁴ kt²	157.4	199.0	23rd	371.5 (2015)

North Indian

September 2021 North Indian Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Gulab:Shaheen-G	TS	September 24-October 1Sep 24-Oct 1	60 mph†	983 mb†
†Value occurred in October

North Indian Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	1	0.3 (3 in 10 Septembers)	2nd (tied with 8 other Septembers)	2 (1972, 2006)
Cyclone Winds ≥ 74 mph (64 kts)	0	0.1 (1 in 10 Septembers)	3rd (tied with 38 other Septembers)	2 (1972)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 40 other Septembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	1.5	0.4 (4 in 10 Septembers)	4th	6.0 (1972)

North Indian Tropical Cyclone Season Counts January-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	3	2.3	7th (tied with 7 other seasons)	5 (2006)
Cyclone Winds ≥ 74 mph (64 kts)	2	0.8 (8 in 10 seasons)	2nd (tied with 5 other seasons)	3 (1972, 2019)
Major Cyclone Winds ≥ 111 mph (96 kts)	1	0.5 (5 in 10 seasons)	2nd (tied with 14 other seasons)	2 (2019)
Accumulated Cyclone Energy ACE×10⁴ kt²	15.3	10.2	9th	42.6 (2019)

South Indian

No South Indian Tropical Cyclones occurred during September 2021.

South Indian Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.2 (2 in 10 Septembers)	9th (tied with 33 other Septembers)	1 (8 Septembers)
Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 Septembers)	2nd (tied with 40 other Septembers)	1 (1993)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 41 other Septembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.3 (3 in 10 Septembers)	9th (tied with 33 other Septembers)	4.5 (1993)

South Indian Tropical Cyclone Season Counts July-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.4 (4 in 10 seasons)	14th (tied with 28 other seasons)	2 (1997, 1999)
Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 seasons)	2nd (tied with 40 other seasons)	1 (1993)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 seasons)	1st (tied with 41 other seasons)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.6 (6 in 10 seasons)	14th (tied with 28 other seasons)	4.5 (1993)

Australia

No Australia Tropical Cyclones occurred during September 2021.

Australia Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.1 (1 in 10 Septembers)	3rd (tied with 39 other Septembers)	1 (2005, 2019)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 41 other Septembers)	0
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 41 other Septembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.1 (1 in 10 Septembers)	3rd (tied with 39 other Septembers)	2.0 (2005)

Australia Tropical Cyclone Season Counts July-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.2 (2 in 10 seasons)	7th (tied with 35 other seasons)	1 (6 seasons)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 seasons)	1st (tied with 41 other seasons)	0
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 seasons)	1st (tied with 41 other seasons)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.1 (1 in 10 seasons)	7th (tied with 35 other seasons)	2.0 (2005)

Southwest Pacific

No Southwest Pacific Tropical Cyclones occurred during September 2021.

Southwest Pacific Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.0 (0 in 10 Septembers)	2nd (tied with 40 other Septembers)	1 (2019)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 41 other Septembers)	0
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Septembers)	1st (tied with 41 other Septembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.0 (0 in 10 Septembers)	2nd (tied with 40 other Septembers)	1.4 (2019)

Southwest Pacific Tropical Cyclone Season Counts July-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.1 (1 in 10 seasons)	4th (tied with 38 other seasons)	1 (1963, 2015, 2016, 2019)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 seasons)	1st (tied with 41 other seasons)	0
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 seasons)	1st (tied with 41 other seasons)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.1 (1 in 10 seasons)	3rd (tied with 39 other seasons)	1.4 (2016)

Global

September 2021 Global Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Larry	3	September 1Sep 1-11	125 mph	955 mb
Conson	TS	September 6Sep 6-11	70 mph	989 mb
Chanthu	5	September 6Sep 6-17	170 mph	908 mb
Mindy	TS	September 8Sep 8-9	45 mph	1004 mb
Olaf	1	September 8Sep 8-11	90 mph	977 mb
Nicholas	1	September 12Sep 12-14	75 mph	989 mb
Odette	TS	September 17Sep 17-18	45 mph	1001 mb
Peter	TS	September 19Sep 19-21	50 mph	1005 mb
Rose	TS	September 19Sep 19-22	50 mph	1004 mb
Sam	4	September 23-October 5Sep 23-Oct 5	155 mph	929 mb
Mindulle	5	September 23-October 2Sep 23-Oct 2	165 mph	908 mb
Not_Named	TS	September 23Sep 23	40 mph	1001 mb
Gulab:Shaheen-G	TS	September 24-October 1Sep 24-Oct 1	60 mph†	983 mb†
Teresa	TS	September 24Sep 24-25	45 mph	1008 mb
Victor	TS	September 29-October 2Sep 29-Oct 2	65 mph†	997 mb†
†Value occurred in October

Global Tropical Cyclone September Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	16	16.4	20th (tied with 3 other Septembers)	22 (2018)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	6	10.0	38th (tied with 3 other Septembers)	15 (2005)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	4	5.3	26th (tied with 4 other Septembers)	9 (1996)
Accumulated Cyclone Energy ACE×10⁴ kt²	157.0	156.8	16th	266.5 (2004)

Global Tropical Cyclone Season Counts January-September 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	75	66.2	5th (tied with 2 other seasons)	83 (2018)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	29	35.8	37th	45 (1990, 1997)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	14	18.8	33rd (tied with 1 other season)	28 (2015)
Accumulated Cyclone Energy ACE×10⁴ kt²	510.9	581.7	26th	842.1 (2004)

Data Description

The data in this report are derived from NCEI's IBTrACS dataset (Knapp et al. 2010; Schreck et al. 2014). IBTrACS tropical cyclone track and intensity data from agencies and sources around the globe. In this report, data from NOAA's National Hurricane Center (NHC) are used for the North Atlantic and East Pacific. The other basins use data from the U.S. Military's Joint Typhoon Warning Center (JTWC).

Historical values use the "best track" data that have been analyzed by forecasters after the season using all available data. Operational procedures and observing systems have changed with time and between regions, which makes these data heterogeneous. Intensity data are generally the most reliable since the early 1970s in the Atlantic (Landsea and Franklin 2013) and since the mid-1980s in other regions (Chu et al. 2002). The number of short-lived storms (≤2 days) has also increased since around 2000 due to improvements in observations and analysis techniques (Landsea et al. 2010).

Values for the current year are provisional values from the operational forecast advisories. IBTrACS obtains these from NCEP's TC Vitals, the NCAR Tropical Cyclone Guidance Project, and NHC provisional data. These values are subject to change during the post-season best track analysis. They also only include 6-hourly storm fixes, which means they may miss special advisories at landfall, peak intensity, etc.

The tropical cyclone seasons in the Southern Hemisphere begin in July and end in June, while the Northern Hemisphere seasons are counted from January to December. Storms are counted in all basins, months, and years in which they occur, which means some storms may appear more than once. However, the global totals only include each storm one time.

References

• Chu, J.-H., C. R. Sampson, A. S. Levine, and E. Fukada, 2002: The joint typhoon warning center tropical cyclone best-tracks, 1945–2000. Naval Research Laboratory, Reference Number NRL/MR/7540-02-16, 22 pp., https://www.metoc.navy.mil/jtwc/products/best-tracks/tc-bt-report.html.
• Knapp, K. R., M. C. Kruk, D. H. Levinson, H. J. Diamond, and C. J. Neumann, 2010: The International Best Track Archive for Climate Stewardship (IBTrACS). Bull. Amer. Meteor. Soc., 91, 363–376, https://doi.org/10.1175/2009BAMS2755.1.
• Landsea, C. W., and J. L. Franklin, 2013: Atlantic Hurricane database uncertainty and presentation of a new database format. Mon. Wea. Rev., 141, 3576–3592, https://doi.org/10.1175/MWR-D-12-00254.1.
• ——, G. A. Vecchi, L. Bengtsson, and T. R. Knutson, 2010: Impact of duration thresholds on Atlantic tropical cyclone counts. J. Climate, 23, 2508–2519, https://doi.org/10.1175/2009JCLI3034.1.
• Schreck, C. J., K. R. Knapp, and J. P. Kossin, 2014: The Impact of Best Track Discrepancies on Global Tropical Cyclone Climatologies using IBTrACS. Mon. Wea. Rev., 142, 3881–3899, https://doi.org/10.1175/MWR-D-14-00021.1.