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Monthly climate in Williamstown, New Jersey, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Williamstown features a humid subtropical climate (Cfa).Temperatures typically range between 2 °C (36 °F) and 26 °C (79 °F) through the year, but rarely can drop to -17 °C (1 °F) or can rise to as high as 36 °C (98 °F).The average annual precipitation amounts to about 1288 mm (50.7 inches) and receives 128 rainy days on the 1 mm (0.04 inches) threshold annually.Williamstown enjoys an average of 3046 hours of sunshine throughout the year, and daylight varies from 9 hours 23 minutes to 14 hours 55 minutes per day.

Monthly average temperatures in Williamstown, New Jersey, United States §

The warmest months in Williamstown are June, July and August, with daily mean temperatures ranging from 23 to 26 °C (74 - 79 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 2 to 5 °C (36 - 41 °F) throughout the day. On average each year, Williamstown experiences 102 days above 25 °C (77.0 °F) and 61 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Williamstown, New Jersey, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 20°C
(69°F)		 25°C
(78°F)		 28°C
(83°F)		 32°C
(90°F)		 34°C
(94°F)		 35°C
(95°F)		 36°C
(98°F)		 35°C
(95°F)		 35°C
(95°F)		 35°C
(95°F)		 24°C
(76°F)		 20°C
(68°F)
Mean maximum 17°C
(63°F)		 20°C
(68°F)		 24°C
(76°F)		 28°C
(83°F)		 33°C
(91°F)		 34°C
(93°F)		 35°C
(96°F)		 34°C
(93°F)		 32°C
(91°F)		 29°C
(84°F)		 24°C
(75°F)		 18°C
(64°F)
Average high 6°C
(43°F)		 9°C
(48°F)		 12°C
(54°F)		 18°C
(64°F)		 23°C
(73°F)		 28°C
(82°F)		 31°C
(87°F)		 29°C
(85°F)		 26°C
(80°F)		 21°C
(70°F)		 13°C
(56°F)		 8°C
(48°F)
Daily mean 2°C
(36°F)		 4°C
(40°F)		 7°C
(45°F)		 13°C
(55°F)		 18°C
(65°F)		 23°C
(74°F)		 26°C
(79°F)		 25°C
(77°F)		 22°C
(72°F)		 17°C
(62°F)		 9°C
(48°F)		 5°C
(41°F)
Average low -2°C
(30°F)		 0°C
(32°F)		 3°C
(37°F)		 8°C
(47°F)		 13°C
(56°F)		 18°C
(65°F)		 22°C
(72°F)		 21°C
(70°F)		 18°C
(64°F)		 12°C
(55°F)		 4°C
(39°F)		 1°C
(33°F)
Mean minimum -12°C
(11°F)		 -10°C
(14°F)		 -5°C
(23°F)		 1°C
(33°F)		 6°C
(43°F)		 12°C
(55°F)		 16°C
(62°F)		 16°C
(61°F)		 10°C
(51°F)		 4°C
(39°F)		 -5°C
(23°F)		 -7°C
(20°F)
Minimum -17°C
(1°F)		 -15°C
(6°F)		 -9°C
(17°F)		 -2°C
(29°F)		 2°C
(36°F)		 10°C
(50°F)		 14°C
(57°F)		 14°C
(58°F)		 7°C
(44°F)		 2°C
(36°F)		 -8°C
(18°F)		 -11°C
(12°F)

Compare climate in Williamstown with other places

Compare temperature, precipitation, sunshine, UV index in Williamstown, New Jersey, United States with other places around the world.

Monthly average precipitation in Williamstown, New Jersey, United States §

Williamstown usually has the most precipitation in May, July and August, with an average of 13 rainy days and 136 mm (5.4 inches) of precipitation per month.The driest months in Williamstown are January, September and November. On average, 77 mm (3.1 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Williamstown, New Jersey, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 60 (2.3) 106 (4.2) 109 (4.3) 99 (3.9) 132 (5.2) 117 (4.6) 136 (5.3) 140 (5.5) 95 (3.7) 116 (4.6) 78 (3.1) 100 (3.9)
Average precipitation days (≥ 1 mm) 8 11 10 11 12 12 13 14 11 9 8 9

Monthly sunshine hours in Williamstown, New Jersey, United States §

The sunniest months in Williamstown are June, July and August, when the sun shines an average of 10 hours 52 minutes a day.Least sunny months in Williamstown: January, February and December receive an average of 5 hours 37 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Williamstown, New Jersey, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 150 178 252 258 289 327 354 318 274 233 225 182
Mean daily daylight hours 9h 42m 10h 42m 11h 58m 13h 16m 14h 23m 14h 55m 14h 37m 13h 39m 12h 23m 11h 5m 9h 57m 9h 23m

Solar UV radiation in Williamstown, New Jersey, United States §

Williamstown experiences the highest level of ultraviolet (UV) radiation in May, June and July, when the maximum UV index can reach values of 10 - 10, which corresponds to the Very High category of sun exposure.January, November and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly Williamstown UV Index data.

Average daily maximum UV levels by month for Williamstown, New Jersey, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 3 5 6 9 10 10 10 9 8 6 4 3