Weather Records on 21 September 1939

308 weather records were set or tied worldwide on 21 September 1939. Highest significance: San Diego Wbo, US.

Key Facts for 21 September 1939

On 21 September 1939, 308 weather records were set or tied at long-record stations worldwide.
225 were record highs and 15 were record lows, counting maximum and minimum temperature.
By timescale, 7 were all-time records, 11 monthly and 290 daily.
San Diego Wbo set a daily record high maximum temperature of 41.1 C (106.0 F) on 21 September 1939.
Across 155 earlier years (1805 to 2026) the same calendar date averaged 452 records.

Record Map

308 stations

308 station records on 21 September 1939 are marked on the map, coloured by record type. Dot size shows the significance score. Made with Natural Earth.

Weather records on 21 September 1939: highest significance records shown on the map
Station	Country	Type	Value	Significance
San Diego Wbo	United States	Record high maximum temperature	41.1 C (106.0 F)	52 of 100 (Notable)
Ranebennur	India	Record daily precipitation	78.0 mm (3.1 in)	49 of 100 (Notable)
Berkeley	United States	Record high minimum temperature	22.2 C (72.0 F)	44 of 100 (Notable)
Riverside Fire STN 3	United States	Record high minimum temperature	26.7 C (80.1 F)	40 of 100 (Notable)
Kurinjipadi	India	Record daily precipitation	66.0 mm (2.6 in)	35 of 100 (Notable)
Denair 3 NNE	United States	Record high minimum temperature	21.7 C (71.1 F)	33 of 100 (Routine)
Santa Barbara	United States	Record high maximum temperature	40.0 C (104.0 F)	32 of 100 (Routine)
Izeleni (Bos)	South Africa	Record daily precipitation	30.5 mm (1.2 in)	31 of 100 (Routine)
Cloverdale	United States	Record high minimum temperature	21.1 C (70.0 F)	30 of 100 (Routine)
Electra P H	United States	Record high minimum temperature	22.8 C (73.0 F)	29 of 100 (Routine)
Hollister 1 SW	United States	Record high minimum temperature	19.4 C (66.9 F)	29 of 100 (Routine)
Le Grand	United States	Record high minimum temperature	22.8 C (73.0 F)	29 of 100 (Routine)
San Diego Wbo	United States	Record high minimum temperature	25.0 C (77.0 F)	29 of 100 (Routine)
Livermore	United States	Record high minimum temperature	20.0 C (68.0 F)	28 of 100 (Routine)
Porterville	United States	Record high minimum temperature	24.4 C (75.9 F)	28 of 100 (Routine)
Saint Helena	United States	Record high minimum temperature	16.7 C (62.1 F)	28 of 100 (Routine)
Sacramento 5 ESE	United States	Record high minimum temperature	22.8 C (73.0 F)	28 of 100 (Routine)
New Westminster	Canada	Record high maximum temperature	26.1 C (79.0 F)	27 of 100 (Routine)
Tuba City	United States	Record high minimum temperature	23.9 C (75.0 F)	27 of 100 (Routine)
McKinley	United States	Record high maximum temperature	37.8 C (100.0 F)	27 of 100 (Routine)
Newman	United States	Record high minimum temperature	20.6 C (69.1 F)	26 of 100 (Routine)
Waimanalo 794	United States	Record low minimum temperature	19.4 C (66.9 F)	26 of 100 (Routine)
Lemon Cove	United States	Record high minimum temperature	22.8 C (73.0 F)	25 of 100 (Routine)
Ashland	United States	Record high minimum temperature	18.9 C (66.0 F)	25 of 100 (Routine)
Chidambaram	India	Record daily precipitation	52.8 mm (2.1 in)	24 of 100 (Routine)
Napa State Hospital	United States	Record high minimum temperature	20.0 C (68.0 F)	24 of 100 (Routine)
Odessa	United States	Record high minimum temperature	15.6 C (60.1 F)	24 of 100 (Routine)
Hood Rvr Exp STN	United States	Record high maximum temperature	34.4 C (93.9 F)	23 of 100 (Routine)
Portland Rfc City	United States	Record high maximum temperature	31.1 C (88.0 F)	23 of 100 (Routine)
Nannilam	India	Record daily precipitation	64.5 mm (2.5 in)	22 of 100 (Routine)
Folsom	United States	Record high minimum temperature	22.2 C (72.0 F)	22 of 100 (Routine)
Healdsburg	United States	Record high minimum temperature	17.8 C (64.0 F)	22 of 100 (Routine)
Spokane Intl AP	United States	Record high minimum temperature	15.0 C (59.0 F)	22 of 100 (Routine)
Marysville (Post Office)	Australia	Record daily precipitation	30.2 mm (1.2 in)	21 of 100 (Routine)
Ottumwa	United States	Record high minimum temperature	20.6 C (69.1 F)	21 of 100 (Routine)
Centralia	United States	Record high maximum temperature	31.7 C (89.1 F)	21 of 100 (Routine)
Roper River Police	Australia	Record daily precipitation	12.7 mm (0.5 in)	20 of 100 (Routine)
Ozena	United States	Record daily precipitation	20.1 mm (0.8 in)	20 of 100 (Routine)
Murrurundi Post Office	Australia	Record daily precipitation	14.5 mm (0.6 in)	20 of 100 (Routine)
Arhangelsk	Russia	Record daily precipitation	13.0 mm (0.5 in)	20 of 100 (Routine)
Blagovescensk	Russia	Record daily precipitation	14.8 mm (0.6 in)	20 of 100 (Routine)
Tiger Creek Ph	United States	Record daily precipitation	21.6 mm (0.9 in)	20 of 100 (Routine)
Carlton Hill	Australia	Record daily precipitation	7.1 mm (0.28 in)	20 of 100 (Routine)
Miranda Downs Station	Australia	Record daily precipitation	2.5 mm (0.10 in)	20 of 100 (Routine)
Owens Gap (T.O.K.)	Australia	Record daily precipitation	12.7 mm (0.5 in)	20 of 100 (Routine)
Szombathely	Hungary	Record daily precipitation	34.9 mm (1.4 in)	20 of 100 (Routine)
Cloverdale	United States	Record high maximum temperature	42.2 C (108.0 F)	20 of 100 (Routine)
El Cajon 2 E	United States	Record high minimum temperature	22.2 C (72.0 F)	20 of 100 (Routine)
Forest Grove	United States	Record high maximum temperature	33.3 C (91.9 F)	20 of 100 (Routine)
Heppner	United States	Record high minimum temperature	14.4 C (57.9 F)	20 of 100 (Routine)
Ellensburg	United States	Record high maximum temperature	33.9 C (93.0 F)	20 of 100 (Routine)
Sixprong	United States	Record high maximum temperature	35.0 C (95.0 F)	20 of 100 (Routine)
Maunawili Rch	United States	Record low minimum temperature	17.8 C (64.0 F)	20 of 100 (Routine)
Donors Hill Station	Australia	Record daily precipitation	0.5 mm (0.02 in)	19 of 100 (Routine)
Lawn Hill	Australia	Record daily precipitation	0.8 mm (0.03 in)	19 of 100 (Routine)
Vernon Coldstream Ranch	Canada	Record high minimum temperature	11.7 C (53.1 F)	19 of 100 (Routine)
Valangiman	India	Record daily precipitation	68.6 mm (2.7 in)	19 of 100 (Routine)
Claremont Pomona Clg	United States	Record high minimum temperature	21.1 C (70.0 F)	19 of 100 (Routine)
Pomona/Fairplex	United States	Record daily precipitation	1.8 mm (0.07 in)	19 of 100 (Routine)
Visalia	United States	Record high minimum temperature	22.2 C (72.0 F)	19 of 100 (Routine)

Counts by Type and Timescale

308 records

Records set or tied on 21 September 1939 by type: Highest daily maximum 123, Lowest daily maximum 2, Highest daily minimum 102, Lowest daily minimum 13, Heaviest daily rainfall 68.

Records on 21 September 1939 by type
Record type	Records
Highest daily maximum	123
Lowest daily maximum	2
Highest daily minimum	102
Lowest daily minimum	13
Heaviest daily rainfall	68
Heaviest daily snowfall	0
Deepest snow cover	0

Records on 21 September 1939 by timescale: all-time 7, monthly 11, daily 290.

How Much Records Were Beaten By

239 broken records

Margins by which the 239 broken records beat the old ones, in degrees Celsius for temperature and millimetres for precipitation and snow; the largest margin was 50.5. Ties are not counted.

Top 20 by Significance

21 September 1939

Top 20 records on 21 September 1939 by significance
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
21 September 1939	San Diego Wbo, US	daily high max	41.1 C (106.0 F)	8.3 C (14.9 F)	55 years	52 of 100 (Notable)
21 September 1939	Ranebennur, IN	daily rain	78.0 mm (3.1 in)	50.1 mm (2.0 in)	32 years	49 of 100 (Notable)
21 September 1939	Berkeley, US	all-time high min	22.2 C (72.0 F)	1.6 C (2.9 F)	38 years	44 of 100 (Notable)
21 September 1939	Riverside Fire STN 3, US	all-time high min	26.7 C (80.1 F)	2.3 C (4.1 F)	30 years	40 of 100 (Notable)
21 September 1939	Kurinjipadi, IN	daily rain	66.0 mm (2.6 in)	50.5 mm (2.0 in)	28 years	35 of 100 (Notable)
21 September 1939	Denair 3 NNE, US	daily high min	21.7 C (71.1 F)	6.7 C (12.1 F)	25 years	33 of 100 (Routine)
21 September 1939	Santa Barbara, US	daily high max	40.0 C (104.0 F)	6.1 C (11.0 F)	41 years	32 of 100 (Routine)
21 September 1939	Izeleni (Bos), ZA	daily rain	30.5 mm (1.2 in)	25.4 mm (1.0 in)	24 years	31 of 100 (Routine)
21 September 1939	Cloverdale, US	daily high min	21.1 C (70.0 F)	5.5 C (9.9 F)	33 years	30 of 100 (Routine)
21 September 1939	Electra P H, US	daily high min	22.8 C (73.0 F)	6.1 C (11.0 F)	26 years	29 of 100 (Routine)
21 September 1939	Hollister 1 SW, US	daily high min	19.4 C (66.9 F)	5.0 C (9.0 F)	25 years	29 of 100 (Routine)
21 September 1939	Le Grand, US	daily high min	22.8 C (73.0 F)	5.6 C (10.1 F)	33 years	29 of 100 (Routine)
21 September 1939	San Diego Wbo, US	all-time high min	25.0 C (77.0 F)	0.6 C (1.1 F)	0 years	29 of 100 (Routine)
21 September 1939	Livermore, US	daily high min	20.0 C (68.0 F)	5.0 C (9.0 F)	25 years	28 of 100 (Routine)
21 September 1939	Porterville, US	daily high min	24.4 C (75.9 F)	6.1 C (11.0 F)	25 years	28 of 100 (Routine)
21 September 1939	Saint Helena, US	daily high min	16.7 C (62.1 F)	5.0 C (9.0 F)	29 years	28 of 100 (Routine)
21 September 1939	Sacramento 5 ESE, US	monthly high min	22.8 C (73.0 F)	0.6 C (1.1 F)	35 years	28 of 100 (Routine)
21 September 1939	New Westminster, CA	daily high max	26.1 C (79.0 F)	1.1 C (2.0 F)	63 years	27 of 100 (Routine)
21 September 1939	Tuba City, US	monthly high min	23.9 C (75.0 F)	2.8 C (5.0 F)	22 years	27 of 100 (Routine)
21 September 1939	McKinley, US	daily high max	37.8 C (100.0 F)	6.7 C (12.1 F)	33 years	27 of 100 (Routine)

Significance is a score from 0 to 100 combining margin, the age of the old record and the length of the station's record. How it is computed.

The Same Date in Other Years

1805 to 1939

Records set or tied on this calendar date in each year from 1805 to 1939. 1939 had 308 records.

Counts for years before the ledger starts come from the same station rules.

Records on 09-21 in each year
Year	Records
1805	1
1812	1
1825	2
1840	1
1841	1
1842	1
1848	1
1854	1
1856	2
1868	1
1872	2
1873	1
1877	1
1878	1
1881	1
1882	1
1884	1
1886	1
1888	2
1889	1
1891	10
1892	1
1893	10
1894	2
1895	3
1896	2
1897	6
1898	6
1899	3
1900	2
1901	5
1902	5
1903	8
1904	20
1905	12
1906	17
1907	10
1908	17
1909	10
1910	8
1911	18
1912	26
1913	37
1914	29
1915	34
1916	48
1917	28
1918	43
1919	54
1920	29
1921	64
1922	35
1923	232
1924	291
1925	278
1926	178
1927	165
1928	81
1929	232
1930	82
1931	681
1932	242
1933	193
1934	492
1935	199
1936	329
1937	487
1938	508
1939	308
1940	908
1941	416
1942	291
1943	407
1944	413
1945	507
1946	176
1947	534
1948	301
1949	298
1950	334
1951	241
1952	430
1953	382
1954	453
1955	752
1956	1,100
1957	366
1958	588
1959	513
1960	418
1961	441
1962	1,085
1963	306
1964	374
1965	1,088
1966	565
1967	577
1968	790
1969	593
1970	708
1971	645
1972	599
1973	421
1974	652
1975	528
1976	694
1977	918
1978	818
1979	736
1980	990
1981	696
1982	1,484
1983	2,207
1984	707
1985	796
1986	671
1987	965
1988	557
1989	1,002
1990	716
1991	1,021
1992	752
1993	911
1994	713
1995	2,002
1996	1,233
1997	1,112
1998	1,481
1999	1,025
2000	884
2001	718
2002	696
2003	959
2004	888
2005	1,143
2006	920
2007	742
2008	740
2009	715
2010	1,290
2011	542
2012	595
2013	769
2014	716
2015	565
2016	989
2017	1,178
2018	1,051
2019	833
2020	580
2021	465
2022	1,049
2023	783
2024	470
2025	591
2026	478

Download the Data

Data for records on 1939-09-21: CSV or JSON. Field meanings are on the data page.

Sources: Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Made with Natural Earth. Public domain map data. Borders are Natural Earth's de facto depiction. Data as of 2026-10-14 (14 October 2026). Records are computed by this site and are not official.

Data as of 2026-10-15. Last revised 15 October 2026 (2026-10-15).

Margin	Records
0 to 10	225
10 to 20	9
20 to 30	2
30 to 40	1
40 to 50	0
50 to 60	2