December 2021 Tropical Cyclones Report

Summary

Global tropical cyclone activity was near normal by all metrics in December with six named storms, including three tropical cyclones, two of which became major tropical cyclones. The accumulated cyclone energy (ACE: an integrated metric of the strength, frequency, and duration of tropical storms) was also near normal.

Both major tropical cyclones in December happened in the West Pacific, which typically only sees a major typhoon every other December on average. Super Typhoon Rai was the most impactful storm of December. It made landfall in the Philippines shortly after rapidly intensifying to category 5 strength. It caused widespread damage and killed hundreds of people. Rai was the sixth category 5 storm globally in 2021 and the fourth in the West Pacific.

No tropical cyclones formed in the South Indian Ocean in December, which usually produces 1.4 storms per December on average. The Australian region had two named storms, which was near normal. Tropical Storm Teratai was briefly active on December 1 and then it reemerged on December 8-9. Tropical Cyclone Ruby reached hurricane strength as it passed near New Caledonia. Ruby also passed into the Southwest Pacific basin where it was the lone tropical cyclone for December, which was still near normal.

North Atlantic

No North Atlantic Tropical Cyclones occurred during December 2021.

North Atlantic Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1851-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.3 (3 in 10 Decembers)	10th (tied with 31 other Decembers)	3 (1887)
Hurricane Winds ≥ 74 mph (64 kts)	0	0.1 (1 in 10 Decembers)	4th (tied with 37 other Decembers)	1 (7 Decembers)
Major Hurricane Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Decembers)	1st (tied with 40 other Decembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.8 (8 in 10 Decembers)	10th (tied with 31 other Decembers)	16.2 (1984)

North Atlantic Tropical Cyclone Season Counts January-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1851-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	21	14.5	3rd	30 (2020)
Hurricane Winds ≥ 74 mph (64 kts)	7	7.2	16th (tied with 6 other seasons)	15 (2005)
Major Hurricane Winds ≥ 111 mph (96 kts)	4	3.2	10th (tied with 3 other seasons)	7 (2005, 2020)
Accumulated Cyclone Energy ACE×10⁴ kt²	145.7	122.8	12th	258.6 (1933)

East Pacific

No East Pacific Tropical Cyclones occurred during December 2021.

East Pacific Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1949-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	0.1 (1 in 10 Decembers)	4th (tied with 37 other Decembers)	1 (5 Decembers)
Hurricane Winds ≥ 74 mph (64 kts)	0	0.0 (0 in 10 Decembers)	2nd (tied with 39 other Decembers)	1 (1957, 1983)
Major Hurricane Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Decembers)	1st (tied with 40 other Decembers)	0
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	0.2 (2 in 10 Decembers)	4th (tied with 37 other Decembers)	11.7 (1957)

East Pacific Tropical Cyclone Season Counts January-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1949-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	19	16.9	16th (tied with 3 other seasons)	27 (1992)
Hurricane Winds ≥ 74 mph (64 kts)	8	8.8	24th (tied with 4 other seasons)	16 (1990, 1992, 2014, 2015)
Major Hurricane Winds ≥ 111 mph (96 kts)	2	4.6	30th (tied with 7 other seasons)	11 (2015)
Accumulated Cyclone Energy ACE×10⁴ kt²	94.0	132.8	30th	318.1 (2018)

West Pacific

December 2021 West Pacific Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Nyatoh	4	November 29-December 4Nov 29-Dec 4	145 mph	933 mb
Rai	5	December 13Dec 13-20	165 mph	915 mb

West Pacific Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1945-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	2	1.5	6th (tied with 17 other Decembers)	4 (1952, 1986, 2001)
Typhoon Winds ≥ 74 mph (64 kts)	2	0.8 (8 in 10 Decembers)	3rd (tied with 7 other Decembers)	3 (1986, 1993)
Major Typhoon Winds ≥ 111 mph (96 kts)	2	0.5 (5 in 10 Decembers)	1st (tied with 3 other Decembers)	2 (9 Decembers)
Accumulated Cyclone Energy ACE×10⁴ kt²	33.9	14.0	6th	72.1 (1959)

West Pacific Tropical Cyclone Season Counts January-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1945-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	23	26.4	32nd (tied with 2 other seasons)	38 (1964)
Typhoon Winds ≥ 74 mph (64 kts)	10	16.2	38th (tied with 1 other season)	26 (1964)
Major Typhoon Winds ≥ 111 mph (96 kts)	5	9.4	37th (tied with 2 other seasons)	16 (2015)
Accumulated Cyclone Energy ACE×10⁴ kt²	207.7	301.4	34th	570.4 (1997)

North Indian

December 2021 North Indian Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Jawad	TS	December 3Dec 3-4	40 mph	997 mb

North Indian Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	1	0.9 (9 in 10 Decembers)	8th (tied with 19 other Decembers)	3 (2005)
Cyclone Winds ≥ 74 mph (64 kts)	0	0.3 (3 in 10 Decembers)	11th (tied with 30 other Decembers)	1 (10 Decembers)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.0 (0 in 10 Decembers)	2nd (tied with 39 other Decembers)	1 (2017)
Accumulated Cyclone Energy ACE×10⁴ kt²	0.7	2.8	24th (tied with 2 other Decembers)	11.0 (2017)

North Indian Tropical Cyclone Season Counts January-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	5	5.5	14th (tied with 13 other seasons)	11 (1992)
Cyclone Winds ≥ 74 mph (64 kts)	3	2.2	7th (tied with 5 other seasons)	6 (2019)
Major Cyclone Winds ≥ 111 mph (96 kts)	1	1.1	9th (tied with 16 other seasons)	5 (2019)
Accumulated Cyclone Energy ACE×10⁴ kt²	16.3	24.7	23rd	93.0 (2019)

South Indian

No South Indian Tropical Cyclones occurred during December 2021.

South Indian Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	1.4	32nd (tied with 10 other Decembers)	4 (1980)
Cyclone Winds ≥ 74 mph (64 kts)	0	0.7 (7 in 10 Decembers)	21st (tied with 21 other Decembers)	3 (2014, 2020)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.5 (5 in 10 Decembers)	13th (tied with 29 other Decembers)	3 (2014)
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	10.1	32nd (tied with 10 other Decembers)	54.9 (2014)

South Indian Tropical Cyclone Season Counts July-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	0	3.0	40th (tied with 2 other seasons)	6 (1997)
Cyclone Winds ≥ 74 mph (64 kts)	0	1.2	29th (tied with 13 other seasons)	3 (7 seasons)
Major Cyclone Winds ≥ 111 mph (96 kts)	0	0.8 (8 in 10 seasons)	18th (tied with 24 other seasons)	3 (2014, 2019)
Accumulated Cyclone Energy ACE×10⁴ kt²	0.0	18.7	40th (tied with 2 other seasons)	71.2 (1997)

Australia

December 2021 Australia Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Teratai	TS	December 1Dec 1	40 mph	1004 mb
Teratai	TS	December 8Dec 8-9	40 mph	999 mb
Ruby	1	December 11Dec 11-14	80 mph	980 mb

Australia Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	3	1.5	3rd (tied with 3 other Decembers)	4 (1985, 1997)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	1	0.8 (8 in 10 Decembers)	7th (tied with 16 other Decembers)	2 (7 Decembers)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.4 (4 in 10 Decembers)	11th (tied with 31 other Decembers)	2 (2014)
Accumulated Cyclone Energy ACE×10⁴ kt²	1.8	8.8	27th	33.7 (1999)

Australia Tropical Cyclone Season Counts July-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	4	2.3	5th (tied with 4 other seasons)	7 (1997)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	1	1.0 (10 in 10 seasons)	9th (tied with 18 other seasons)	3 (1996, 1999)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.4 (4 in 10 seasons)	12th (tied with 30 other seasons)	2 (2014)
Accumulated Cyclone Energy ACE×10⁴ kt²	3.1	10.5	29th	42.6 (1999)

Southwest Pacific

December 2021 Southwest Pacific Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Ruby	1	December 11Dec 11-14	80 mph†	980 mb†
†Value occurred in the Southwest Pacific

Southwest Pacific Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	1	0.7 (7 in 10 Decembers)	9th (tied with 13 other Decembers)	3 (6 Decembers)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	1	0.5 (5 in 10 Decembers)	5th (tied with 10 other Decembers)	2 (1987, 1992, 1993, 2013)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.3 (3 in 10 Decembers)	8th (tied with 34 other Decembers)	2 (1992, 1993, 2013)
Accumulated Cyclone Energy ACE×10⁴ kt²	1.5	6.9	17th	46.9 (1992)

Southwest Pacific Tropical Cyclone Season Counts July-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1956-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	1	1.3	17th (tied with 8 other seasons)	6 (1998)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	1	0.8 (8 in 10 seasons)	8th (tied with 10 other seasons)	4 (1998)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	0	0.4 (4 in 10 seasons)	11th (tied with 31 other seasons)	2 (1992, 1993, 2013)
Accumulated Cyclone Energy ACE×10⁴ kt²	1.5	9.5	20th	58.7 (1992)

Global

December 2021 Global Tropical Cyclones

Name	Maximum CategoryMax Cat	Dates >39 mph	Maximum Sustained Winds	Minimum Central Pressure
Nyatoh	4	November 29-December 4Nov 29-Dec 4	145 mph	933 mb
Teratai	TS	December 1Dec 1	40 mph	1004 mb
Jawad	TS	December 3Dec 3-4	40 mph	997 mb
Teratai	TS	December 8Dec 8-9	40 mph	999 mb
Ruby	1	December 11Dec 11-14	80 mph	980 mb
Rai	5	December 13Dec 13-20	165 mph	915 mb

Global Tropical Cyclone December Counts

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	6	6.1	17th (tied with 9 other Decembers)	10 (1984, 1996, 1998)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	3	3.1	14th (tied with 9 other Decembers)	6 (1991, 1993, 1998, 2019)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	2	1.6	6th (tied with 10 other Decembers)	4 (1991, 2012, 2013, 2019)
Accumulated Cyclone Energy ACE×10⁴ kt²	37.9	44.3	21st	88.7 (2012)

Global Tropical Cyclone Season Counts January-December 2021

Storm Type	Count	1991-2020 Mean	1981-2021 Rank*	1972-2021 Record
Tropical Storm Winds ≥ 39 mph (34 kts)	94	88.2	10th (tied with 1 other season)	106 (2020)
Tropical Cyclone Winds ≥ 74 mph (64 kts)	37	48.1	41st	59 (1990, 1992, 2018)
Major Tropical Cyclone Winds ≥ 111 mph (96 kts)	16	25.7	39th (tied with 1 other season)	39 (2015)
Accumulated Cyclone Energy ACE×10⁴ kt²	614.4	789.0	33rd	1,163.1 (1992)

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.