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Monthly climate in Portsmouth, Rhode Island, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Portsmouth features a humid subtropical climate (Cfa).Temperatures typically range between 1 °C (35 °F) and 22 °C (73 °F) through the year, but rarely can drop to -17 °C (2 °F) or can rise to as high as 29 °C (84 °F).The average annual precipitation amounts to about 1455 mm (57.3 inches) and receives 132 rainy days on the 1 mm (0.04 inches) threshold annually.Portsmouth enjoys an average of 3039 hours of sunshine throughout the year, and daylight varies from 9 hours 12 minutes to 15 hours 7 minutes per day.

Monthly average temperatures in Portsmouth, Rhode Island, United States §

The warmest months in Portsmouth are July, August and September, with daily mean temperatures ranging from 20 to 22 °C (67 - 73 °F) throughout the day. The coldest temperatures usually occur in January, February and March, when daily mean temperatures range from 1 to 3 °C (35 - 39 °F) throughout the day. On average each year, Portsmouth experiences 12 days above 25 °C (77.0 °F) and 51 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Portsmouth, Rhode Island, 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 14°C
(57°F)		 12°C
(54°F)		 15°C
(58°F)		 17°C
(64°F)		 22°C
(72°F)		 25°C
(78°F)		 29°C
(84°F)		 28°C
(83°F)		 27°C
(80°F)		 23°C
(74°F)		 20°C
(68°F)		 16°C
(61°F)
Mean maximum 11°C
(52°F)		 10°C
(51°F)		 12°C
(53°F)		 14°C
(58°F)		 20°C
(69°F)		 24°C
(75°F)		 27°C
(81°F)		 27°C
(81°F)		 25°C
(77°F)		 22°C
(72°F)		 18°C
(65°F)		 14°C
(58°F)
Average high 4°C
(40°F)		 4°C
(40°F)		 6°C
(43°F)		 10°C
(50°F)		 14°C
(58°F)		 19°C
(67°F)		 23°C
(74°F)		 24°C
(75°F)		 21°C
(70°F)		 17°C
(63°F)		 11°C
(53°F)		 6°C
(44°F)
Daily mean 1°C
(35°F)		 2°C
(36°F)		 3°C
(39°F)		 8°C
(46°F)		 12°C
(55°F)		 18°C
(64°F)		 22°C
(72°F)		 22°C
(73°F)		 20°C
(67°F)		 15°C
(60°F)		 9°C
(48°F)		 4°C
(39°F)
Average low -1°C
(30°F)		 -1°C
(31°F)		 1°C
(34°F)		 6°C
(43°F)		 11°C
(52°F)		 16°C
(62°F)		 21°C
(69°F)		 21°C
(70°F)		 18°C
(64°F)		 13°C
(56°F)		 6°C
(43°F)		 1°C
(35°F)
Mean minimum -13°C
(10°F)		 -10°C
(14°F)		 -7°C
(20°F)		 2°C
(35°F)		 6°C
(43°F)		 12°C
(54°F)		 17°C
(63°F)		 17°C
(63°F)		 13°C
(55°F)		 6°C
(43°F)		 -3°C
(27°F)		 -7°C
(20°F)
Minimum -17°C
(2°F)		 -14°C
(7°F)		 -9°C
(16°F)		 0°C
(32°F)		 4°C
(39°F)		 11°C
(51°F)		 15°C
(60°F)		 16°C
(61°F)		 11°C
(52°F)		 3°C
(37°F)		 -7°C
(20°F)		 -13°C
(9°F)

Compare climate in Portsmouth with other places

Compare temperature, precipitation, sunshine, UV index in Portsmouth, Rhode Island, United States with other places around the world.

Monthly average precipitation in Portsmouth, Rhode Island, United States §

Portsmouth usually has the most precipitation in April, October and December, with an average of 12 rainy days and 154 mm (6.1 inches) of precipitation per month.The driest months in Portsmouth are January, July and August. On average, 96 mm (3.8 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Portsmouth, Rhode Island, 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) 95 (3.8) 121 (4.8) 119 (4.7) 147 (5.8) 132 (5.2) 104 (4.1) 104 (4.1) 89 (3.5) 110 (4.3) 169 (6.7) 117 (4.6) 147 (5.8)
Average precipitation days (≥ 1 mm) 9 12 10 12 14 10 11 10 10 13 10 11

Monthly sunshine hours in Portsmouth, Rhode Island, United States §

The sunniest months in Portsmouth are June, July and August, when the sun shines an average of 10 hours 52 minutes a day.Least sunny months in Portsmouth: January, February and December receive an average of 5 hours 39 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Portsmouth, Rhode Island, 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 149 188 260 249 294 325 346 328 282 230 206 176
Mean daily daylight hours 9h 32m 10h 36m 11h 58m 13h 21m 14h 32m 15h 7m 14h 48m 13h 45m 12h 25m 11h 2m 9h 49m 9h 12m

Solar UV radiation in Portsmouth, Rhode Island, United States §

Portsmouth experiences the highest level of ultraviolet (UV) radiation in May, June and August, when the maximum UV index can reach values of 9 - 10, which corresponds to the Very High category of sun exposure.January, November and December are in the Low / 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 Portsmouth UV Index data.

Average daily maximum UV levels by month for Portsmouth, Rhode Island, 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 8 9 10 9 9 8 6 4 2