Williamstown climate — normals and trends

Q: What is the climate of Williamstown?

Williamstown has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 13.1 °C and it receives 1,079 mm of precipitation per year.

Q: What is the hottest day ever recorded in Williamstown?

The hottest day measured in Williamstown between 1940 and 2025 was 3 July 1966, reaching 40.1 °C.

Q: What is the coldest day in Williamstown?

The coldest day measured in Williamstown between 1940 and 2025 was 22 January 1984, at -25.0 °C.

Q: Does it snow in Williamstown?

Yes. Williamstown gets on average 45.3 cm of snow per year and has around 74 frost days.

Q: Has the climate of Williamstown warmed?

Yes: Williamstown warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.

Q: What is the wettest day in Williamstown?

The wettest day measured in Williamstown between 1940 and 2025 was 16 September 1999, with 136 mm of rain in 24 hours.

Q: What was the windiest day in Williamstown?

The windiest day measured in Williamstown between 1940 and 2025 was 29 October 2012, with winds reaching 52.3 km/h.

Q: What is the warmest month in Williamstown?

The warmest month in Williamstown is July (25.0 °C on average); the coldest is January (0.9 °C).

Q: How much does it rain in Williamstown?

Williamstown receives on average 1,079 mm of precipitation per year, spread over about 117 rainy days.

Q: Is it sunny in Williamstown?

Williamstown gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.

Williamstown (United States) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 13.1 °C and it receives 1,079 mm of precipitation per year.

These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.

The warmest month is July (25.0 °C on average) and the coldest is January (0.9 °C). Rainfall peaks in August.

Williamstown averages 74 frost days, 39 hot days (≥ 30 °C) and 117 rainy days per year.

Williamstown has warmed by +1.6 °C between 1940 and 2025, or +0.19 °C per decade. This trend is statistically significant.

The number of frost days there went from about 81 to 67 per year over the period.

The hottest day of the period reached 40.1 °C (on 3 July 1966) and the coldest -25.0 °C (on 22 January 1984).

Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.

Climate normals · ERA5

WilliamstownNew Jersey

coords: 39.69°, -75.00°
period: 1940–2025 · 86 yrs

CfaHumid subtropicalWarmest monthJulyColdest monthJanuaryWettest monthAugustDriest monthFebruary

Mean daily temperature

13.1°C

Average daily high

17.7°C

Average daily low

8.8°C

Annual rainfall

1,079mm

Sunshine / day

8.9h

Mean relative humidity

66%

Average peak wind

17.9km/h

Seasonal range

24.1°C

Frost days (< 0 °C)

74 d/yr

Hot days (≥ 30 °C)

39 d/yr

Rainy days (≥ 1 mm)

117 d/yr

Annual snowfall

45.3 cm

Average feels-like high

16.3 °C

Average feels-like low

6.5 °C

Average peak gust

39.2 km/h

Tropical nights (≥ 20 °C)

52 d/yr

Solar radiation

14.9 MJ/m²

Has the climate changed?

One stripe per year, 1940 to 2025

+1.6 °C

since 1940

+0.2 °C per decade · r² = 0.38 · p = < 0.001

19402025

Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).

A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.

Records for the period

Hottest day

40.1 °C

3 July 1966

Coldest day

-25.0 °C

22 January 1984

Wettest day

136 mm

16 September 1999

Windiest day

52.3 km/h

29 October 2012

Strongest gust

141.1 km/h

25 November 1950

Hottest feels-like

45.2 °C

15 July 1995

Coldest feels-like

-29.9 °C

22 January 1961

Snowiest day

38.4 cm

20 March 1958

Sunniest day

14.1 h

23 June 2007

Year	Hottest day	Coldest day	Annual mean	Rainfall	Hot days	Frost days
2025	38.8 °C24 June 2025	-12.1 °C23 January 2025	13.7 °C	950 mm	49	74
2024	36.7 °C16 July 2024	-13.3 °C23 December 2024	14.5 °C	998 mm	45	60
2023	35.7 °C27 July 2023	-10.3 °C4 February 2023	14.6 °C	1,092 mm	47	40
2022	35.2 °C9 August 2022	-14.0 °C31 January 2022	14.0 °C	1,211 mm	51	85
2021	35.1 °C30 June 2021	-8.7 °C8 February 2021	14.4 °C	1,102 mm	54	63
2020	36.2 °C3 July 2020	-9.9 °C15 February 2020	14.6 °C	1,334 mm	53	51
2019	36.5 °C21 July 2019	-14.8 °C31 January 2019	14.1 °C	1,194 mm	54	74
2018	35.0 °C2 July 2018	-17.1 °C7 January 2018	13.9 °C	1,635 mm	49	69
2017	35.0 °C13 June 2017	-14.7 °C9 January 2017	14.4 °C	1,040 mm	46	58
2016	35.7 °C14 August 2016	-13.2 °C14 February 2016	14.2 °C	992 mm	54	63
2015	35.6 °C23 June 2015	-16.2 °C20 February 2015	13.9 °C	1,057 mm	46	74
2014	34.3 °C18 June 2014	-20.9 °C4 January 2014	12.5 °C	1,087 mm	27	81
2013	35.1 °C18 July 2013	-11.6 °C23 January 2013	13.2 °C	1,025 mm	34	76
2012	37.9 °C7 July 2012	-10.5 °C4 January 2012	14.7 °C	923 mm	48	51
2011	39.7 °C22 July 2011	-11.1 °C24 January 2011	14.3 °C	1,303 mm	52	71
2010	38.9 °C6 July 2010	-10.5 °C7 February 2010	14.1 °C	1,061 mm	68	78
2009	33.7 °C10 August 2009	-14.5 °C17 January 2009	13.0 °C	1,263 mm	22	79
2008	37.2 °C10 June 2008	-11.1 °C11 February 2008	13.7 °C	1,025 mm	50	70
2007	36.0 °C8 August 2007	-12.1 °C6 February 2007	13.6 °C	1,024 mm	47	74
2006	36.1 °C18 July 2006	-10.0 °C19 February 2006	14.2 °C	1,124 mm	42	50
2005	37.7 °C27 July 2005	-17.1 °C28 January 2005	13.2 °C	966 mm	44	75
2004	32.9 °C9 June 2004	-15.5 °C10 January 2004	13.1 °C	1,104 mm	29	78
2003	34.9 °C26 June 2003	-13.2 °C18 January 2003	12.5 °C	1,369 mm	25	83
2002	37.1 °C4 July 2002	-11.3 °C7 December 2002	14.0 °C	1,057 mm	54	63
2001	37.3 °C9 August 2001	-10.9 °C3 January 2001	13.7 °C	829 mm	32	68
2000	34.7 °C11 June 2000	-13.5 °C18 January 2000	12.7 °C	976 mm	22	84
1999	37.2 °C5 July 1999	-10.7 °C2 January 1999	13.7 °C	1,054 mm	45	66
1998	35.4 °C22 July 1998	-9.7 °C25 December 1998	14.4 °C	914 mm	48	41
1997	35.1 °C16 August 1997	-15.0 °C19 January 1997	12.8 °C	965 mm	39	67
1996	34.5 °C20 May 1996	-18.0 °C5 February 1996	12.5 °C	1,382 mm	17	71
1995	38.1 °C15 July 1995	-15.1 °C6 February 1995	13.4 °C	902 mm	53	77
1994	36.7 °C15 June 1994	-19.5 °C19 January 1994	13.5 °C	1,099 mm	44	68
1993	37.3 °C10 July 1993	-15.6 °C7 February 1993	13.2 °C	1,045 mm	50	76
1992	35.4 °C14 July 1992	-11.4 °C19 January 1992	12.4 °C	988 mm	21	75
1991	36.7 °C29 June 1991	-11.3 °C23 January 1991	14.1 °C	1,032 mm	56	68
1990	36.2 °C5 July 1990	-11.7 °C26 February 1990	14.2 °C	1,001 mm	37	52
1989	34.0 °C27 June 1989	-14.4 °C23 December 1989	12.6 °C	1,380 mm	30	89
1988	36.5 °C15 August 1988	-16.2 °C11 January 1988	12.5 °C	917 mm	54	86
1987	35.4 °C21 July 1987	-22.2 °C28 January 1987	12.9 °C	1,059 mm	45	72
1986	36.7 °C7 July 1986	-11.8 °C28 January 1986	13.0 °C	1,048 mm	40	78
1985	35.2 °C14 August 1985	-20.9 °C21 January 1985	13.2 °C	831 mm	29	81
1984	34.8 °C9 June 1984	-25.0 °C22 January 1984	12.9 °C	1,232 mm	34	76
1983	37.2 °C20 August 1983	-17.1 °C25 December 1983	13.1 °C	1,378 mm	54	62
1982	34.9 °C19 July 1982	-20.5 °C17 January 1982	12.5 °C	977 mm	19	78
1981	34.5 °C9 July 1981	-17.4 °C12 January 1981	12.3 °C	1,023 mm	24	82
1980	36.1 °C16 July 1980	-14.9 °C26 December 1980	12.6 °C	840 mm	54	88
1979	34.1 °C10 August 1979	-21.8 °C18 February 1979	12.8 °C	1,311 mm	24	71
1978	35.2 °C23 July 1978	-17.3 °C5 February 1978	11.8 °C	1,294 mm	26	88
1977	36.0 °C19 July 1977	-19.6 °C17 January 1977	12.7 °C	1,143 mm	42	81
1976	33.0 °C18 April 1976	-14.4 °C23 January 1976	12.4 °C	911 mm	35	91
1975	35.3 °C2 August 1975	-9.9 °C24 December 1975	13.3 °C	1,313 mm	29	74
1974	34.9 °C10 July 1974	-10.6 °C5 February 1974	13.2 °C	951 mm	37	66
1973	36.1 °C28 August 1973	-13.1 °C17 February 1973	13.6 °C	1,199 mm	39	57
1972	35.1 °C21 July 1972	-14.8 °C16 January 1972	12.5 °C	1,304 mm	30	74
1971	35.9 °C8 July 1971	-12.6 °C2 February 1971	13.2 °C	1,227 mm	36	67
1970	34.2 °C23 September 1970	-16.3 °C9 January 1970	12.8 °C	905 mm	43	77
1969	34.7 °C29 May 1969	-10.6 °C28 January 1969	12.5 °C	1,181 mm	35	90
1968	37.7 °C1 July 1968	-19.3 °C12 January 1968	12.6 °C	904 mm	42	81
1967	32.8 °C16 June 1967	-19.2 °C13 February 1967	11.8 °C	998 mm	20	82
1966	40.1 °C3 July 1966	-15.8 °C29 January 1966	12.3 °C	888 mm	46	85
1965	34.5 °C25 July 1965	-16.9 °C15 January 1965	12.2 °C	679 mm	41	90
1964	35.5 °C10 June 1964	-16.8 °C15 January 1964	12.6 °C	1,005 mm	45	84
1963	35.4 °C27 June 1963	-18.8 °C29 January 1963	12.0 °C	916 mm	29	86
1962	35.2 °C19 May 1962	-15.9 °C11 February 1962	11.9 °C	1,074 mm	29	92
1961	33.7 °C13 June 1961	-24.4 °C22 January 1961	12.5 °C	1,183 mm	41	79
1960	33.1 °C3 August 1960	-15.3 °C24 December 1960	12.3 °C	1,084 mm	26	97
1959	37.3 °C30 June 1959	-13.2 °C23 December 1959	13.4 °C	1,008 mm	54	76
1958	33.8 °C31 July 1958	-15.2 °C17 February 1958	11.9 °C	1,373 mm	31	75
1957	37.4 °C22 July 1957	-17.5 °C18 January 1957	13.2 °C	912 mm	48	62
1956	36.6 °C2 July 1956	-9.8 °C28 January 1956	12.6 °C	1,101 mm	34	66
1955	36.5 °C22 July 1955	-17.1 °C3 February 1955	13.0 °C	928 mm	45	88
1954	37.2 °C31 July 1954	-18.8 °C18 January 1954	13.1 °C	936 mm	32	71
1953	37.3 °C31 August 1953	-9.0 °C18 December 1953	13.9 °C	1,096 mm	48	56
1952	37.8 °C26 June 1952	-13.4 °C30 January 1952	13.2 °C	1,256 mm	38	58
1951	33.7 °C27 July 1951	-12.9 °C17 December 1951	13.1 °C	1,039 mm	40	71
1950	33.5 °C27 June 1950	-12.2 °C27 December 1950	12.6 °C	1,012 mm	28	84
1949	37.3 °C28 July 1949	-10.7 °C12 February 1949	14.0 °C	856 mm	48	57
1948	36.7 °C26 August 1948	-19.0 °C19 January 1948	12.3 °C	1,325 mm	26	78
1947	33.6 °C14 August 1947	-13.4 °C5 February 1947	12.6 °C	964 mm	23	84
1946	32.5 °C20 July 1946	-10.5 °C23 January 1946	13.4 °C	957 mm	17	60
1945	35.3 °C1 July 1945	-15.9 °C25 January 1945	12.7 °C	1,258 mm	24	77
1944	35.2 °C5 August 1944	-10.2 °C17 January 1944	12.7 °C	1,173 mm	47	83
1943	34.2 °C26 June 1943	-15.4 °C15 February 1943	12.4 °C	894 mm	48	91
1942	34.9 °C19 July 1942	-17.4 °C11 January 1942	12.7 °C	1,256 mm	28	79
1941	35.6 °C28 July 1941	-9.0 °C1 March 1941	12.8 °C	969 mm	37	90
1940	35.0 °C26 July 1940	-14.6 °C20 January 1940	11.7 °C	1,194 mm	16	86

Normals computed over complete calendar years 1940–2025.

A specific year

Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?

Year

Across the whole year

Average daily high

18.2 °C

+0.5 °C

Hot days (≥ 30 °C)

49 d/yr

+10

Frost days (< 0 °C)

74 d/yr

Annual rainfall

950 mm

-129 mm

Month by month

	High	vs. normal	Precipitation	vs. normal
Jan	3.1 °C	-1.6 °C	32 mm	-49 mm
Feb	6.6 °C	+0.2 °C	63 mm	-13 mm
Mar	15.1 °C	+4.0 °C	97 mm	-2 mm
Apr	18.9 °C	+1.7 °C	88 mm	-4 mm
May	22.6 °C	+0.1 °C	130 mm	+38 mm
Jun	28.6 °C	+1.3 °C	76 mm	-12 mm
Jul	31.3 °C	+1.6 °C	180 mm	+78 mm
Aug	27.7 °C	-0.9 °C	35 mm	-71 mm
Sep	26.3 °C	+1.2 °C	83 mm	-5 mm
Oct	19.8 °C	+0.7 °C	58 mm	-25 mm
Nov	13.0 °C	0.0 °C	45 mm	-39 mm
Dec	5.0 °C	-2.1 °C	63 mm	-27 mm

The year's extremes

Hottest day

38.8 °C

24 Jun 2025

Coldest day

-12.1 °C

23 Jan 2025

Wettest day

35.5 mm

30 Oct 2025

Windiest day

40.1 km/h

16 Feb 2025

Strongest gust

88.6 km/h

16 Feb 2025

Hottest feels-like

42.5 °C

23 Jun 2025

Coldest feels-like

-16.5 °C

21 Jan 2025

Snowiest day

8.9 cm

14 Dec 2025

Sunniest day

14.1 h

4 Jul 2025

What was the weather like that day?

Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.

Date

Frequently asked questions

What is the climate of Williamstown?

Williamstown has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 13.1 °C and it receives 1,079 mm of precipitation per year.

What is the hottest day ever recorded in Williamstown?

The hottest day measured in Williamstown between 1940 and 2025 was 3 July 1966, reaching 40.1 °C.

What is the coldest day in Williamstown?

The coldest day measured in Williamstown between 1940 and 2025 was 22 January 1984, at -25.0 °C.

Does it snow in Williamstown?

Yes. Williamstown gets on average 45.3 cm of snow per year and has around 74 frost days.

Has the climate of Williamstown warmed?

Yes: Williamstown warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.

What is the wettest day in Williamstown?

The wettest day measured in Williamstown between 1940 and 2025 was 16 September 1999, with 136 mm of rain in 24 hours.

What was the windiest day in Williamstown?

The windiest day measured in Williamstown between 1940 and 2025 was 29 October 2012, with winds reaching 52.3 km/h.

What is the warmest month in Williamstown?

The warmest month in Williamstown is July (25.0 °C on average); the coldest is January (0.9 °C).

How much does it rain in Williamstown?

Williamstown receives on average 1,079 mm of precipitation per year, spread over about 117 rainy days.

Is it sunny in Williamstown?

Williamstown gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.

What is the biggest single-day snowfall in Williamstown?

The heaviest 24-hour snowfall measured in Williamstown between 1940 and 2025 was 20 March 1958, with 38.4 cm.

Are there tropical nights in Williamstown?

Yes: Williamstown has on average 52 tropical nights per year (temperature staying above 20 °C), over 1940-2025.

What was the most extreme apparent temperature in Williamstown?

In Williamstown, between 1940 and 2025, the highest apparent temperature reached 45.2 °C on 15 July 1995, and the lowest was -29.9 °C on 22 January 1961.

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