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Monthly climate in Rialto, California, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Rialto features a hot-summer Mediterranean climate (Csa).Temperatures typically range between 11 °C (51 °F) and 26 °C (79 °F) through the year, but rarely can drop to -3 °C (27 °F) or can rise to as high as 44 °C (111 °F).The average annual precipitation amounts to about 407 mm (16.0 inches) and receives 41 rainy days on the 1 mm (0.04 inches) threshold annually.Rialto enjoys an average of 3646 hours of sunshine throughout the year, and daylight varies from 9 hours 54 minutes to 14 hours 22 minutes per day.

Monthly average temperatures in Rialto, California, United States §

The warmest months in Rialto are July, August and September, 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 11 to 11 °C (51 - 52 °F) throughout the day. On average each year, Rialto experiences 146 days above 25 °C (77.0 °F) and 2 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Rialto, California, 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 28°C
(82°F)		 27°C
(81°F)		 29°C
(85°F)		 33°C
(92°F)		 33°C
(92°F)		 39°C
(102°F)		 42°C
(109°F)		 40°C
(103°F)		 44°C
(111°F)		 37°C
(100°F)		 31°C
(89°F)		 27°C
(80°F)
Mean maximum 24°C
(75°F)		 24°C
(76°F)		 27°C
(80°F)		 31°C
(89°F)		 32°C
(89°F)		 35°C
(95°F)		 38°C
(101°F)		 38°C
(101°F)		 39°C
(102°F)		 34°C
(93°F)		 30°C
(86°F)		 25°C
(76°F)
Average high 17°C
(63°F)		 17°C
(63°F)		 18°C
(65°F)		 22°C
(72°F)		 24°C
(75°F)		 29°C
(85°F)		 33°C
(91°F)		 33°C
(92°F)		 31°C
(87°F)		 26°C
(80°F)		 22°C
(72°F)		 17°C
(63°F)
Daily mean 11°C
(51°F)		 11°C
(52°F)		 12°C
(54°F)		 16°C
(61°F)		 18°C
(64°F)		 22°C
(72°F)		 26°C
(78°F)		 26°C
(79°F)		 23°C
(74°F)		 19°C
(66°F)		 15°C
(59°F)		 11°C
(51°F)
Average low 6°C
(43°F)		 5°C
(42°F)		 7°C
(45°F)		 10°C
(50°F)		 12°C
(54°F)		 16°C
(61°F)		 20°C
(68°F)		 20°C
(68°F)		 17°C
(64°F)		 13°C
(55°F)		 9°C
(49°F)		 6°C
(42°F)
Mean minimum 0°C
(33°F)		 0°C
(33°F)		 2°C
(35°F)		 5°C
(42°F)		 7°C
(44°F)		 11°C
(52°F)		 16°C
(61°F)		 16°C
(61°F)		 13°C
(55°F)		 7°C
(44°F)		 4°C
(40°F)		 0°C
(32°F)
Minimum -3°C
(27°F)		 -1°C
(30°F)		 -0°C
(32°F)		 4°C
(39°F)		 4°C
(40°F)		 10°C
(51°F)		 13°C
(56°F)		 15°C
(59°F)		 10°C
(50°F)		 5°C
(41°F)		 2°C
(35°F)		 -1°C
(30°F)

Compare climate in Rialto with other places

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

Monthly average precipitation in Rialto, California, United States §

Rialto usually has the most precipitation in January, March and December, with an average of 6 rainy days and 71 mm (2.8 inches) of precipitation per month.The driest months in Rialto are June, August and September. On average, 8 mm (0.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Rialto, California, 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) 70 (2.8) 70 (2.7) 75 (2.9) 31 (1.2) 18 (0.7) 3 (0.1) 11 (0.4) 10 (0.4) 10 (0.4) 11 (0.4) 28 (1.1) 70 (2.7)
Average precipitation days (≥ 1 mm) 6 6 9 3 3 1 2 1 1 2 2 5

Monthly sunshine hours in Rialto, California, United States §

The sunniest months in Rialto are May, June and July, when the sun shines an average of 12 hours 14 minutes a day.Least sunny months in Rialto: January, February and December receive an average of 7 hours 15 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Rialto, California, 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 189 243 294 326 367 377 381 362 321 298 256 226
Mean daily daylight hours 10h 9m 10h 58m 11h 59m 13h 3m 13h 56m 14h 22m 14h 8m 13h 20m 12h 20m 11h 16m 10h 22m 9h 54m

Solar UV radiation in Rialto, California, United States §

Rialto experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 11 - 12, which corresponds to the Extreme 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 5. For more detailed information, check out our hourly Rialto UV Index data.

Average daily maximum UV levels by month for Rialto, California, 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) 4 6 9 10 11 12 12 11 10 8 5 4