Ontario, OR: December

31 December 2025: December 2025 averaged 37.5°F in Ontario, OR, the warmest December on record, in 71 years since 1945 (1946 excluded: 26 of 31 days missing; 1983 excluded: 6 of 31 days missing; 1985 excluded: 4 of 31 days missing; 7 more years excluded for missing days); provisional.

December 2025

Mean temperature: 37.5°F; Warmest on record; Warmest of 71, provisional
Precipitation: 2.35 in; Wettest since 2024; 14th wettest of 77

A normal December in Ontario, OR (1991 to 2020): 1.14 in of precipitation, between 0.47 in and 2.66 in in eight years of ten.

The mean temperature of every December in Ontario, OR since 1945: 37.5°F in 2025, the highest of them all.

Every year, ranked, as a table

Every December in Ontario, OR from 1945 to 2025, 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
2025	37.5	1	45.4	1	29.7	7	2.35	14	0
2024	35.1	11	39.4	36	30.8	2	2.73	9	0
2023	35.9	9	41.5	12	30.2	4	0.96	50	0
2022	28.8	48	33.8	65	23.7	34	2.88	6	0
2021	33.5	18	40.1	24	26.9	16	1.25	39	0
2020	31.2	33	39.6	32	22.8	42	0.39	70	0
2019	36.1	7	41.9	10	30.3	3	1.01	45	0
2018	34	16	40.5	18	27.5	13	0.98	48	0
2017	28.4	54	35.1	60	21.8	47	0.54	65	0
2016	19.4	71	27.2	77	11.5	75	1.95	20	0
2015	31	34	37.8	44	24.2	32	2.85	7	0
2014	36.2	5	42.4	8	30.1	5	2.54	10	0
2013	19.7	70	28.1	76	11.4	76	0.45	68	0
2012	33.4	19	40.7	15	26.1	19	0.95	51	0
2011	28.7	52	40.3	23	17.1	65	0.34	71	0
2010	27	61	33.9	63	20.1	57	3.43	3	0
2009	25.5	64	32.6	69	18.5	60	1.88	21	0
2008	27.8	57	36.6	50	19	59	1.30	36	0
2007	31.3	31	37.9	42	24.6	29	1.14	42	0
2006	29.2	46	37.2	48	21.3	51	1.46	29	0
2005	24	66	30.8	72	17.3	62	3.47	2	0
2004	34.2	14	40.6	17	27.8	11	0.48	67	1
2003	35.5	10	42.3	9	28.8	10	1.38	33	0
2002	36.7	2	43.3	4	30.1	5	1.68	26	0
2001	30.9	35	36.2	55	25.6	22	0.97	49	0
2000	30.7	37	35.7	57	25.8	20	0.81	56	1
1999	29.7	44	34.9	61	24.5	30	1.00	46	0
1998	28.6	53	35.6	58	21.6	49	0.69	61	0
1997	30	40	37.4	46	22.6	43			0
1996	32.2	23	40.5	18	23.5	38			3
1995			39.8	29			1.98	19	5
1994			32.8	68	16.4	69	1.26	37	4
1993					23.6	37	0.70	60	4
1992			33.9	63	16.8	67	1.88	21	5
1991	29.9	43	38.8	38	21	52			2
1990					6.5	77	0.32	72	6
1989	28.8	48	40.4	20	17.1	65	0.04	76	0
1988			31.7	70	16.7	68	2.17	15	4
1987			40.4	20	23	40	1.26	37	4
1986	27.2	60	36.3	52	17.9	61	trace	77	2
1985			20.5	78	1.7	78	0.79	57	4
1984	21.7	68	30.5	73	13	73	1.08	43	0
1983			31.6	71			4.34	1	6
1982	28.8	48	36.1	56	21.8	47	2.74	8	2
1981	32.8	22	40	26	25.5	23	3.43	3	0
1980	31.5	30	37.7	45	25.4	24	1.46	29	1
1979	31.7	27	39.6	32	23.8	33	0.78	59	0
1978	24.3	65	33.6	67	15	70	0.57	64	0
1977	36.1	7	43	6	29.1	9	1.81	24	0
1976	26	63	39.9	28	12	74	0.05	74	0
1975	29.6	45	35.5	59	23.7	34	1.35	34	1
1974	30	40	37.4	46	22.6	43	1.31	35	0
1973	36.6	3	43.7	3	29.5	8	2.11	17	0
1972	22.3	67	30.5	73	14.2	71	2.13	16	0
1971	28.4	54	36.3	52	20.5	55	1.17	40	0
1970	31.6	28	39.5	34	23.7	34	1.64	27	0
1969	34.3	13	43.2	5	25.3	25	2.52	12	0
1968	31.9	26	39.7	31	24.5	30	2.53	11	1
1967	26.8	62	36.3	52	17.2	63	0.59	63	1
1966	33.2	20	39.8	29	26.6	17	1.59	28	0
1965	30.9	35	40.4	20	21.4	50	0.05	74	0
1964	33	21	41.3	14	24.8	26	3.18	5	0
1963	27.8	57	33.7	66	21.9	45	1.16	41	0
1962	34.5	12	41.4	13	27.5	13	1.44	31	0
1961	31.3	31	39.2	37	23.4	39	0.91	52	0
1960	30.1	39	40	26	20.2	56	0.52	66	0
1959	28.9	47	40.7	15	17.2	63	0.79	57	0
1958	36.2	5	44.4	2	27.7	12	0.83	54	2
1957	33.8	17	40.1	24	27.5	13	1.70	25	0
1956	30.6	38	38.2	40	23	40	0.62	62	0
1955	34.1	15	42.5	7	25.7	21	2.02	18	0
1954	28.2	56	36.5	51	20	58	0.99	47	0
1953	31.6	28	38.5	39	24.7	28	1.05	44	0
1952	32.1	25	37.9	42	26.4	18	0.87	53	0
1951	27.5	59	34.3	62	20.7	54	1.88	21	0
1950	36.3	4	41.6	11	30.9	1	1.41	32	0
1949	30	40	38.1	41	21.9	45	0.42	69	0
1948	21.7	68	30.4	75	13.1	72	0.83	54	0
1947	32.2	23	39.5	34	24.8	26	0.23	73	0
1946									26
1945	28.8	48	36.7	49	20.8	53	2.48	13	0

Warmest, coldest, wettest and driest

Warmest
Year	Mean, °F
2025	37.5
2002	36.7
1973	36.6
1950	36.3
2014	36.2
1958	36.2
2019	36.1
1977	36.1
2023	35.9
2003	35.5

Coldest
Year	Mean, °F
2016	19.4
2013	19.7
1984	21.7
1948	21.7
1972	22.3
2005	24
1978	24.3
2009	25.5
1976	26
1967	26.8

Wettest
Year	Precipitation, in
1983	4.34
2005	3.47
2010	3.43
1981	3.43
1964	3.18
2022	2.88
2015	2.85
1982	2.74
2024	2.73
2014	2.54

Driest
Year	Precipitation, in
1986	trace
1989	0.04
1976	0.05
1965	0.05
1947	0.23
1990	0.32
2011	0.34
2020	0.39
1949	0.42
2013	0.45

The hottest, coldest and wettest days

Hottest day: 58°F; 17 December 2025
Coldest night: 20°F; 31 December 2025, 1 December 2025
Wettest day: 1.14 in; 21 December 2025

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Every answer in words

December 2025 brought 2.35 in of precipitation in Ontario, OR, the wettest December since 2024, 14th wettest of 77.
The hottest day of December 2025 in Ontario, OR: 58°F on Wednesday 17 December 2025.
The coldest night of December 2025 in Ontario, OR: a low of 20°F on Wednesday 31 December 2025 and Monday 1 December 2025.
The wettest day of December 2025 in Ontario, OR: 1.14 in on Sunday 21 December 2025.