Casper, WY: September

30 September 2026: September 2026 averaged 62.7°F in Casper, WY, the warmest September since 2024, 11th warmest of 87.

September 2026

Mean temperature: 62.7°F; Warmest since 2024; 11th warmest of 87
Precipitation: 0.76 in; Wettest since 2025; 41st wettest of 87

A normal September in Casper, WY (1991 to 2020): a mean temperature of 59.3°F, between 55.7°F and 61.9°F in eight years of ten and 0.88 in of precipitation, between 0.28 in and 1.62 in in eight years of ten.

The mean temperature of every September in Casper, WY since 1940: 62.7°F in 2026; the highest is 64.7°F, in 1998.

Normal range, 55.7 to 61.9°F

Every year, ranked, as a table

Every September in Casper, WY from 1940 to 2026, ranked: the mean temperature, the mean high and the mean low from the warmest, the precipitation from the wettest; a year missing more than a tenth of its days is not ranked.

Year	Mean, °F	Rank	High, °F	Rank	Low, °F	Rank	Precipitation, in	Rank
2026	62.7	11	79.5	13	45.9	13	0.76	41
2025	61.5	20	77.5	31	45.4	18	2.55	6
2024	63.3	5	82.4	1	44.2	24	0.24	74
2023	61.2	23	78.9	16	43.5	30	0.59	50
2022	62.3	13	79.9	8	44.6	21	0.81	38
2021	61.7	19	80.6	6	42.8	47	0.79	39
2020	57.8	57	75.5	41	40	70	0.54	52
2019	61.5	20	78.1	27	44.8	20	1.41	19
2018	59.9	37	78.8	19	41	65	0.28	70
2017	57.2	59	72.7	65	41.7	60	1.42	17
2016	58.8	46	74.3	49	43.3	34	1.55	14
2015	64.4	2	82.3	2	46.4	9	0.19	81
2014	59.4	41	76.6	36	42.2	53	0.64	49
2013	61.8	18	76.4	37	47.2	4	1.47	15
2012	61.2	23	79.4	14	42.9	43	0.31	66
2011	59.9	37	78.1	27	41.8	58	0.10	85
2010	60	35	79.8	9	40.1	69	0.28	70
2009	59.3	43	78.3	23	40.3	68	1.62	13
2008	55.7	72	73	62	38.5	82	0.74	42
2007	59.2	44	75.2	43	43.1	40	0.71	45
2006	54.5	79	70.2	73	38.9	78	1.40	20
2005	61.1	25	78.6	21	43.6	29	0.23	75
2004	58.6	47	73.9	54	43.3	34	1.75	10
2003	55.3	74	70.7	68	39.9	71	1.38	22
2002	58.6	47	74.3	49	42.9	43	1.12	28
2001	61.3	22	78.1	27	44.4	23	1.09	30
2000	57.1	60	73.3	59	41	65	1.65	12
1999	54.4	80	70.2	73	38.5	82	1.30	24
1998	64.7	1	80.9	5	48.5	3	0.79	39
1997	59.9	37	74.2	51	45.7	15	1.21	25
1996	55.8	71	72.4	67	39.2	77	0.47	56
1995	58	55	72.7	65	43.3	34	2.56	5
1994	62.8	10	79.8	9	45.8	14	0.68	46
1993	58.1	54	73	62	43.3	34	0.97	34
1992	61.1	25	78.9	16	43.3	34	0.29	69
1991	59.4	41	75.5	41	43.4	32	0.40	59
1990	63.2	6	80.1	7	46.3	10	0.52	54
1989	58.2	52	73.4	58	42.9	43	3.22	3
1988	58	55	73.6	56	42.3	51	0.74	42
1987	58.6	47	75.8	40	41.5	62	0.59	50
1986	55.4	73	68.4	81	42.5	50	1.31	23
1985	53.4	84	67.2	85	39.6	72	1.09	30
1984	52.5	85	69.3	77	35.7	86	0.50	55
1983	60.3	32	78.3	23	42.3	51	0.20	80
1982	56.9	62	70.7	68	43.1	40	3.40	1
1981	62	17	79.8	9	44.2	24	0.23	75
1980	59.6	40	77.2	34	42.1	56	0.10	85
1979	62.1	15	81.3	4	42.9	43	0.18	82
1978	60.1	34	76.9	35	43.4	32	0.26	72
1977	60.3	32	78.5	22	42.1	56	0.30	67
1976	59.2	44	74.2	51	44.2	24	1.15	26
1975	56.7	63	74.4	48	38.9	78	0.11	84
1974	54.3	81	70	76	38.7	81	0.83	37
1973	55	76	67.8	83	42.2	53	3.28	2
1972	56.7	63	73.8	55	39.6	72	0.37	61
1971	53.9	83	69.2	79	38.5	82	0.74	42
1970	54.7	77	70.5	72	38.9	78	0.21	78
1969	63.2	6	81.4	3	45.1	19	0.16	83
1968	56.5	66	73.6	56	39.3	76	0.30	67
1967	61	27	76.3	38	45.6	16	1.67	11
1966	62.2	14	78.3	23	46	12	0.39	60
1965	47.6	87	61.2	87	34.1	87	2.07	8
1964	56.1	70	72.8	64	39.4	75	0.34	62
1963	64.1	4	79.2	15	49	2	0.33	65
1962	58.4	50	74.1	53	42.7	48	1.14	27
1961	51.4	86	64.3	86	38.5	82	2.46	7
1960	60.7	30	74.8	45	46.6	8	0.41	58
1959	56.2	67	69.3	77	43.1	40	1.99	9
1958	60	35	75.9	39	44.2	24	0.34	62
1957	56.2	67	70.6	71	41.7	60	1.08	32
1956	61	27	78	30	44	28	0.07	87
1955	60.6	31	75	44	46.1	11	0.65	48
1954	62.5	12	78.3	23	46.7	6	0.23	75
1953	62.1	15	78.7	20	45.6	16	0.21	78
1952	63.2	6	79.7	12	46.7	6	0.25	73
1951	55.3	74	70.2	73	40.4	67	1.12	28
1950	56.2	67	68.9	80	43.5	30	3.11	4
1949	57.1	60	74.7	46	39.5	74	0.66	47
1948	63.1	9	78.9	16	47.2	4	0.87	36
1947	61	27	77.5	31	44.5	22	0.34	62
1946	58.2	52	73.1	61	43.3	34	1.43	16
1945	54.3	81	67.4	84	41.1	64	1.39	21
1944	57.6	58	73.3	59	41.8	58	1.08	32
1943	58.4	50	74.6	47	42.2	53	0.88	35
1942	56.6	65	70.7	68	42.6	49	0.54	52
1941	54.7	77	68.1	82	41.4	63	0.42	57
1940	64.3	3	77.3	33	51.3	1	1.42	17

Warmest, coldest, wettest and driest

Warmest
Year	Mean, °F
1998	64.7
2015	64.4
1940	64.3
1963	64.1
2024	63.3
1990	63.2
1969	63.2
1952	63.2
1948	63.1
1994	62.8

Coldest
Year	Mean, °F
1965	47.6
1961	51.4
1984	52.5
1985	53.4
1971	53.9
1974	54.3
1945	54.3
1999	54.4
2006	54.5
1970	54.7
More years share the last value

Wettest
Year	Precipitation, in
1982	3.40
1973	3.28
1989	3.22
1950	3.11
1995	2.56
2025	2.55
1961	2.46
1965	2.07
1959	1.99
2004	1.75

Driest
Year	Precipitation, in
1956	0.07
2011	0.10
1980	0.10
1975	0.11
1969	0.16
1979	0.18
2015	0.19
1983	0.20
1970	0.21
1953	0.21

The hottest, coldest and wettest days

Hottest day: 91°F; 6 September 2026, 5 September 2026
Coldest night: 36°F; 30 September 2026, 15 September 2026, 9 September 2026
Wettest day: 0.35 in; 13 September 2026

Every month, season and year

Months

Seasons

Years

Casper, WY the day's answers

All-time records

Every answer in words

September 2026 brought 0.76 in of precipitation in Casper, WY, the wettest September since 2025, 41st wettest of 87.
The hottest day of September 2026 in Casper, WY: 91°F on Sunday 6 September 2026 and Saturday 5 September 2026.
The coldest night of September 2026 in Casper, WY: a low of 36°F on Wednesday 30 September 2026, Tuesday 15 September 2026 and Wednesday 9 September 2026.
The wettest day of September 2026 in Casper, WY: 0.35 in on Sunday 13 September 2026.