Boise, ID: September

30 September 2026: September 2026 averaged 65.6°F in Boise, ID, the warmest September since 2025, tied 39th warmest of 150 (with 1987 and 1949).

September 2026

Mean temperature: 65.6°F; Warmest since 2025; 39th warmest of 150
Precipitation: 0.36 in; Wettest since 2025; 71st wettest of 149

A normal September in Boise, ID (1991 to 2020): a mean temperature of 65.9°F, between 63.3°F and 68.8°F in eight years of ten and 0.28 in of precipitation, between 0.01 in and 0.92 in in eight years of ten.

The mean temperature of every September in Boise, ID since 1877: 65.6°F in 2026; the highest is 71.4°F, in 2011.

Normal range, 63.3 to 68.8°F

Every year, ranked, as a table

Every September in Boise, ID from 1875 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	Days missing
2026	65.6	39	78.4	67	52.7	23	0.36	71	0
2025	70.7	4	83.9	8	57.5	2	0.81	32	0
2024	69.8	7	83.3	11	56.2	7	0.20	96	0
2023	68.2	14	81	35	55.4	8	0.45	60	0
2022	71.2	2	85.8	4	56.6	4	0.24	88	0
2021	66.5	27	81.5	29	51.5	30	0.37	69	0
2020	68.7	9	83.3	11	54.1	14	0.04	127	0
2019	65	52	77.3	81	52.6	24	0.84	30	0
2018	65.5	42	79.9	50	51.1	35	0.00	147	0
2017	66.2	28	78.5	64	53.9	15	0.56	51	0
2016	63.9	63	76.7	87	51	37	0.21	94	0
2015	66.6	24	80.1	49	53.1	20	0.51	55	0
2014	67.6	17	80.5	43	54.8	10	0.92	27	0
2013	66.6	24	77.9	74	55.3	9	1.75	10	0
2012	68.6	11	83.5	9	53.7	17	0.05	123	0
2011	71.4	1	86.4	1	56.3	6	0.09	117	0
2010	67.6	17	82	21	53.2	19	0.01	136	0
2009	70.6	5	84.5	6	56.6	4	0.01	136	0
2008	66.1	30	80.2	48	51.9	25	0.94	26	0
2007	64.7	54	78.5	64	50.9	39	0.65	42	0
2006	65.4	44	79.2	56	51.6	29	0.12	108	0
2005	63.3	72	77.5	77	49.1	69	0.32	75	0
2004	63.6	68	76.3	98	51	37	0.25	85	0
2003	66.7	22	80.6	41	52.8	22	0.04	127	0
2002	65.1	50	79	57	51.3	33	0.39	65	0
2001	68.4	13	82.8	14	53.9	15	0.44	61	0
2000	63	82	76.4	94	49.5	63	0.60	48	0
1999	64	62	78.9	59	49.1	69	0.00	147	0
1998	69.8	7	81.8	25	57.7	1	1.96	7	0
1997	67.7	16	81	35	54.4	12	0.67	41	0
1996	61.8	101	75.1	115	48.4	83	0.46	59	0
1995	65.7	35	80.9	37	50.5	44	0.22	92	0
1994	66.8	21	83.2	13	50.4	46	0.10	113	0
1993	63	82	79.5	54	46.5	112	trace	143	0
1992	63.4	71	78.7	61	48.1	89	0.30	79	0
1991	65.7	35	81.1	34	50.4	46	0.21	94	0
1990	69.9	6	86.2	3	53.5	18	0.50	57	0
1989	63.3	72	78.7	61	47.9	92	1.20	18	0
1988	61.7	103	77.2	82	46.1	117	0.24	88	0
1987	65.6	39	82.2	20	49	73	0.00	147	0
1986	57.3	144	69.1	150	45.6	125	2.93	1	0
1985	56.2	149	68.8	151	43.6	145	1.81	9	0
1984	60	122	74.6	120	45.5	126	0.69	39	0
1983	60.8	117	76.2	100	45.4	128	0.65	42	0
1982	60.4	119	73.9	128	46.8	110	1.38	15	0
1981	63.6	68	79	57	48.3	85	0.36	71	0
1980	62.5	90	76.4	94	48.7	79	1.59	11	0
1979	67.3	19	83.5	9	51.1	35	0.04	127	0
1978	61.4	107	74.8	117	47.9	92	0.89	29	0
1977	62	96	75.5	111	48.4	83	1.20	18	0
1976	64.1	59	77.5	77	50.7	42	2.11	5	0
1975	65.5	42	82.4	19	48.6	81	0.01	136	0
1974	65.3	45	81.8	25	48.8	76	trace	143	0
1973	63.1	77	76.9	86	49.3	65	0.82	31	0
1972	58.7	136	71.5	141	46	120	1.11	21	0
1971	59.1	132	72.5	134	45.8	123	0.64	45	0
1970	57.8	140	71.8	137	43.8	142	1.00	24	0
1969	64.2	58	78.1	70	50.2	50	0.68	40	0
1968	63	82	76.7	87	49.2	66	0.10	113	0
1967	68.6	11	82.8	14	54.4	12	0.58	50	0
1966	66.2	28	81.2	32	51.2	34	0.19	98	0
1965	57.1	146	70.1	149	44.1	140	0.55	52	0
1964	59.6	126	74.1	124	45	133	0.70	38	0
1963	70.9	3	84.5	6	57.3	3	0.75	37	0
1962	65.2	48	80.8	39	49.6	62	0.40	63	0
1961	57.2	145	70.8	146	43.5	146	0.79	34	0
1960	66	32	81.9	22	50	53	0.29	80	0
1959	59.7	124	71.3	144	48.1	89	2.54	2	0
1958	62	96	76.2	100	47.8	96	0.12	108	0
1957	65.3	45	80.6	41	50	53	0.06	120	0
1956	64.1	59	79.5	54	48.8	76	0.02	133	0
1955	62.5	90	77	85	47.9	92	0.12	108	0
1954	61.5	106	76.7	87	46.4	115	0.08	118	0
1953	66	32	81.6	27	50.3	49	0.02	133	0
1952	65.3	45	80.9	37	49.8	57	0.05	123	0
1951	63.6	68	78.1	70	49.1	69	0.01	136	0
1950	63.1	77	76.5	92	49.8	57	0.92	27	0
1949	65.6	39	80.7	40	50.5	44	0.19	98	0
1948	61.9	98	76.5	92	47.2	106	0.31	78	0
1947	62.9	86	77.5	77	48.2	88	0.80	33	0
1946	61	113	76	103	46	120	0.16	102	0
1945	59.9	123	74.7	119	45.1	131	0.44	61	0
1944	63.7	64	77.7	75	49.8	57	0.16	102	0
1943	66.6	24	82.5	18	50.8	41	trace	143	0
1942	63.2	74	78.7	61	47.7	98	0.01	136	0
1941	57.9	139	71.1	145	44.7	135	0.22	92	0
1940	63.1	77	74.4	122	51.9	25	1.85	8	0
1939	64.3	56	78.5	64	50.1	52	1.53	12	0
1938	68.7	9	82.8	14	54.5	11	0.34	74	0
1937	65.7	35	80.4	44	50.9	39	0.39	65	0
1936	61.9	98	76.3	98	47.6	102	0.07	119	0
1935	67	20	82.6	17	51.4	32	0.10	113	0
1934	61.4	107	75.5	111	47.2	106	0.04	127	0
1933	61.2	112	75.7	108	46.6	111	0.12	108	0
1932	64.1	59	79.9	50	48.3	85	0.02	133	0
1931	62.5	90	75.8	105	49.2	66	0.60	48	0
1930	63.2	74	76.6	91	49.7	61	0.96	25	0
1929	58.8	135	72.2	135	45.5	126	0.26	83	0
1928	64.3	56	79.7	52	48.9	74	0.25	85	0
1927	59.6	126	71.8	137	47.3	104	1.39	13	0
1926	57.1	146	70.7	147	43.5	146	0.10	113	0
1925	61.3	111	74	125	48.7	79	1.19	20	0
1924	63.7	64	78.4	67	48.9	74	0.24	88	0
1923	65.7	35	79.6	53	51.8	27	0.55	52	0
1922	66.1	30	81.9	22	50.2	50	0.01	136	0
1921	57.6	142	71.4	142	43.7	144	0.61	47	0
1920	63.2	74	76.4	94	50	53	0.64	45	0
1919	61.7	103	75.5	111	47.9	92	0.79	34	0
1918	65.2	48	77.2	82	53.1	20	2.32	3	0
1917	66	32	80.3	46	51.7	28	1.39	13	0
1916	62.5	90	76.7	87	48.3	85	0.05	123	0
1915	60.4	119	73.2	130	47.6	102	0.26	83	0
1914	61.4	107	75.1	115	47.7	98	0.35	73	0
1913	62.1	95	76.1	102	48.1	89	0.65	42	0
1912	57.7	141	70.2	148	45.2	130	0.77	36	0
1911	60.1	121	73.2	130	47.1	108	0.04	127	0
1910	61.8	101	74.8	117	48.8	76	0.50	57	0
1909	63.1	77	75.8	105	50.4	46	0.51	55	0
1908	62.6	89	75.7	108	49.5	63	1.26	17	0
1907	61.4	107	75.5	111	47.3	104	0.14	105	0
1906	64.4	55	78.8	60	50	53	0.32	75	0
1905	63.7	64	78.2	69	49.1	69	0.19	98	0
1904	64.8	53	80.3	46	49.2	66	0.38	68	0
1903	59.7	124	73.7	129	45.7	124	0.54	54	0
1902	62.3	94	77.6	76	47	109	0.03	132	0
1901	58.2	138	71.8	137	44.6	136	0.37	69	0
1900	59.5	128	73.1	132	45.9	122	1.06	22	0
1899	65.1	50	81.6	27	48.6	81	0.28	81	0
1898	61.9	98	77.4	80	46.4	115	0.01	136	0
1897	61.6	105	77.1	84	46.1	117	1.04	23	0
1896	59.4	130	74.5	121	44.2	139	0.28	81	0
1895	56.7	148	71.9	136	41.5	149	0.32	75	0
1894	59.2	131	74	125	44.3	138	0.40	63	0
1893	59.1	132	71.6	140	46.5	112	2.26	4	0
1892	63	82	81.3	30	44.6	136	0.18	101	0
1891	62.8	87	78	73	47.7	98	0.05	123	0
1890	61	113	78.1	70	43.8	142	0.16	102	0
1889	58.3	137	75.9	104	40.6	150	0.06	120	0
1888	68.1	15	85.6	5	50.6	43	0.06	120	0
1887	63.1	77	81.2	32	45	133	0.14	105	0
1886	59	134	75.8	105	42.2	148	trace	143	0
1885	62.7	88	75.6	110	49.8	57	0.39	65	0
1884	55.3	150	65.2	152	45.4	128	2.11	5	0
1883	63.7	64	81.3	30	46.1	117	0.20	96	0
1882	61	113	74.3	123	47.8	96	1.36	16	0
1881	57.6	142	71.4	142	43.9	141	0.25	85	0
1880	60.7	118	76.4	94	45.1	131	0.11	112	0
1879	66.7	22	81.9	22	51.5	30	0.14	105	0
1878	59.5	128	72.6	133	46.5	112	0.24	88	0
1877	60.9	116	74	125	47.7	98			0
1876			80.4	44					30
1875			86.4	1					30

Warmest, coldest, wettest and driest

Warmest
Year	Mean, °F
2011	71.4
2022	71.2
1963	70.9
2025	70.7
2009	70.6
1990	69.9
2024	69.8
1998	69.8
2020	68.7
1938	68.7

Coldest
Year	Mean, °F
1884	55.3
1985	56.2
1895	56.7
1965	57.1
1926	57.1
1961	57.2
1986	57.3
1921	57.6
1881	57.6
1912	57.7

Wettest
Year	Precipitation, in
1986	2.93
1959	2.54
1918	2.32
1893	2.26
1976	2.11
1884	2.11
1998	1.96
1940	1.85
1985	1.81
2013	1.75

Driest
Year	Precipitation, in
2018	0.00
1999	0.00
1987	0.00
1993	trace
1974	trace
1943	trace
1886	trace
2010	0.01
2009	0.01
1975	0.01
More years share the last value

The hottest, coldest and wettest days

Hottest day: 94°F; 24 September 2026
Coldest night: 43°F; 26 September 2026
Wettest day: 0.17 in; 4 September 2026

Every month, season and year

Months

Seasons

Years

Boise, ID the day's answers

All-time records

Every answer in words

September 2026 brought 0.36 in of precipitation in Boise, ID, the wettest September since 2025, tied 71st wettest of 149 (with 1981).
The hottest day of September 2026 in Boise, ID: 94°F on Thursday 24 September 2026.
The coldest night of September 2026 in Boise, ID: a low of 43°F on Saturday 26 September 2026.
The wettest day of September 2026 in Boise, ID: 0.17 in on Friday 4 September 2026.