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Monthly climate in Roy, Washington, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Roy features a warm-summer Mediterranean climate (Csb).Temperatures typically range between 4 °C (40 °F) and 18 °C (66 °F) through the year, but rarely can drop to -11 °C (12 °F) or can rise to as high as 39 °C (103 °F).The average annual precipitation amounts to about 1389 mm (54.7 inches) and receives 153 rainy days on the 1 mm (0.04 inches) threshold annually.Roy enjoys an average of 2617 hours of sunshine throughout the year, and daylight varies from 8 hours 33 minutes to 15 hours 48 minutes per day.

Monthly average temperatures in Roy, Washington, United States §

The warmest months in Roy are June, July and August, with daily mean temperatures ranging from 16 to 18 °C (60 - 66 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 4 to 5 °C (40 - 41 °F) throughout the day. On average each year, Roy experiences 29 days above 25 °C (77.0 °F) and 27 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Roy, Washington, 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
(58°F)		 14°C
(58°F)		 23°C
(73°F)		 25°C
(78°F)		 28°C
(83°F)		 39°C
(103°F)		 33°C
(91°F)		 34°C
(93°F)		 30°C
(85°F)		 23°C
(74°F)		 17°C
(63°F)		 14°C
(58°F)
Mean maximum 13°C
(56°F)		 12°C
(54°F)		 17°C
(64°F)		 21°C
(71°F)		 26°C
(78°F)		 30°C
(86°F)		 30°C
(87°F)		 32°C
(90°F)		 27°C
(82°F)		 20°C
(68°F)		 16°C
(61°F)		 12°C
(55°F)
Average high 8°C
(46°F)		 7°C
(45°F)		 11°C
(51°F)		 14°C
(57°F)		 18°C
(64°F)		 20°C
(69°F)		 24°C
(75°F)		 24°C
(76°F)		 20°C
(69°F)		 14°C
(58°F)		 10°C
(51°F)		 7°C
(45°F)
Daily mean 5°C
(41°F)		 4°C
(40°F)		 7°C
(44°F)		 9°C
(49°F)		 13°C
(55°F)		 16°C
(60°F)		 18°C
(65°F)		 18°C
(66°F)		 16°C
(60°F)		 10°C
(51°F)		 7°C
(45°F)		 5°C
(41°F)
Average low 3°C
(37°F)		 2°C
(35°F)		 3°C
(38°F)		 5°C
(42°F)		 9°C
(48°F)		 11°C
(52°F)		 13°C
(55°F)		 13°C
(56°F)		 11°C
(53°F)		 7°C
(44°F)		 5°C
(41°F)		 3°C
(37°F)
Mean minimum -4°C
(25°F)		 -5°C
(23°F)		 -2°C
(29°F)		 0°C
(32°F)		 4°C
(40°F)		 7°C
(45°F)		 10°C
(50°F)		 9°C
(49°F)		 7°C
(45°F)		 1°C
(34°F)		 -1°C
(30°F)		 -4°C
(25°F)
Minimum -11°C
(12°F)		 -10°C
(15°F)		 -3°C
(26°F)		 -2°C
(29°F)		 3°C
(38°F)		 6°C
(43°F)		 9°C
(48°F)		 9°C
(48°F)		 6°C
(42°F)		 -3°C
(28°F)		 -3°C
(27°F)		 -8°C
(17°F)

Compare climate in Roy with other places

Compare temperature, precipitation, sunshine, UV index in Roy, Washington, United States with other places around the world.

Monthly average precipitation in Roy, Washington, United States §

Roy usually has the most precipitation in January, February and December, with an average of 17 rainy days and 191 mm (7.5 inches) of precipitation per month.The driest months in Roy are June, July and August. On average, 27 mm (1.1 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Roy, Washington, 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) 183 (7.2) 189 (7.4) 136 (5.4) 118 (4.7) 68 (2.7) 58 (2.3) 11 (0.4) 13 (0.5) 90 (3.5) 142 (5.6) 180 (7.1) 201 (7.9)
Average precipitation days (≥ 1 mm) 16 18 18 15 12 8 2 3 10 14 18 19

Monthly sunshine hours in Roy, Washington, United States §

The sunniest months in Roy are June, July and August, when the sun shines an average of 11 hours 10 minutes a day.Least sunny months in Roy: January, November and December receive an average of 3 hours 6 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Roy, Washington, 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 80 117 198 229 304 316 372 339 258 193 113 92
Mean daily daylight hours 8h 59m 10h 18m 11h 57m 13h 38m 15h 5m 15h 48m 15h 24m 14h 6m 12h 29m 10h 48m 9h 19m 8h 33m

Solar UV radiation in Roy, Washington, United States §

Roy experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 8 - 9, which corresponds to the Very High category of sun exposure.January, February and December are in the Low / Moderate exposure category. In these months, the maximum values of the UV index do not exceed 3. For more detailed information, check out our hourly Roy UV Index data.

Average daily maximum UV levels by month for Roy, Washington, 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) 2 3 5 6 8 9 9 8 7 5 3 2