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Monthly climate in Hercules, California, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Hercules features a warm-summer Mediterranean climate (Csb).Temperatures typically range between 10 °C (50 °F) and 20 °C (68 °F) through the year, but rarely can drop to -2 °C (29 °F) or can rise to as high as 43 °C (111 °F).The average annual precipitation amounts to about 487 mm (19.2 inches) and receives 45 rainy days on the 1 mm (0.04 inches) threshold annually.Hercules enjoys an average of 3400 hours of sunshine throughout the year, and daylight varies from 9 hours 33 minutes to 14 hours 44 minutes per day.

Monthly average temperatures in Hercules, California, United States §

The warmest months in Hercules are June, August and September, with daily mean temperatures ranging from 19 to 20 °C (67 - 68 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 10 to 11 °C (50 - 53 °F) throughout the day. On average each year, Hercules experiences 106 days above 25 °C (77.0 °F) and 0 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Hercules, 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 25°C
(78°F)		 27°C
(80°F)		 30°C
(85°F)		 32°C
(91°F)		 36°C
(97°F)		 40°C
(104°F)		 37°C
(99°F)		 41°C
(105°F)		 43°C
(111°F)		 36°C
(97°F)		 29°C
(85°F)		 24°C
(75°F)
Mean maximum 20°C
(68°F)		 23°C
(74°F)		 27°C
(80°F)		 30°C
(87°F)		 33°C
(91°F)		 36°C
(97°F)		 34°C
(93°F)		 36°C
(98°F)		 38°C
(101°F)		 33°C
(91°F)		 25°C
(77°F)		 20°C
(68°F)
Average high 15°C
(59°F)		 17°C
(63°F)		 18°C
(65°F)		 21°C
(70°F)		 24°C
(75°F)		 27°C
(81°F)		 27°C
(81°F)		 28°C
(82°F)		 28°C
(83°F)		 26°C
(78°F)		 19°C
(67°F)		 15°C
(59°F)
Daily mean 10°C
(50°F)		 11°C
(53°F)		 12°C
(54°F)		 15°C
(59°F)		 17°C
(63°F)		 19°C
(67°F)		 19°C
(67°F)		 20°C
(68°F)		 20°C
(68°F)		 18°C
(64°F)		 13°C
(56°F)		 10°C
(50°F)
Average low 6°C
(43°F)		 6°C
(44°F)		 7°C
(46°F)		 9°C
(49°F)		 11°C
(52°F)		 13°C
(56°F)		 13°C
(56°F)		 14°C
(58°F)		 14°C
(57°F)		 11°C
(52°F)		 8°C
(46°F)		 6°C
(43°F)
Mean minimum 0°C
(33°F)		 1°C
(34°F)		 2°C
(37°F)		 5°C
(41°F)		 8°C
(47°F)		 11°C
(51°F)		 12°C
(54°F)		 11°C
(53°F)		 9°C
(49°F)		 6°C
(43°F)		 3°C
(37°F)		 1°C
(35°F)
Minimum -2°C
(29°F)		 -0°C
(32°F)		 2°C
(35°F)		 3°C
(38°F)		 6°C
(42°F)		 10°C
(50°F)		 11°C
(53°F)		 10°C
(51°F)		 8°C
(46°F)		 4°C
(40°F)		 1°C
(34°F)		 0°C
(32°F)

Compare climate in Hercules with other places

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

Monthly average precipitation in Hercules, California, United States §

Hercules usually has the most precipitation in January, February and December, with an average of 7 rainy days and 97 mm (3.8 inches) of precipitation per month.The driest months in Hercules are July, August and September. On average, 1 mm (0.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Hercules, 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) 101 (4.0) 101 (4.0) 77 (3.0) 32 (1.3) 18 (0.7) 1 (0.1) 0 (0.0) 0 (0.0) 1 (0.0) 25 (1.0) 41 (1.6) 88 (3.5)
Average precipitation days (≥ 1 mm) 8 7 9 4 2 0 0 0 0 2 5 8

Monthly sunshine hours in Hercules, California, United States §

The sunniest months in Hercules are May, June and July, when the sun shines an average of 12 hours 10 minutes a day.Least sunny months in Hercules: January, February and December receive an average of 6 hours 5 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Hercules, 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 148 215 262 298 356 378 386 348 311 279 224 190
Mean daily daylight hours 9h 51m 10h 47m 11h 59m 13h 12m 14h 14m 14h 44m 14h 27m 13h 32m 12h 22m 11h 9m 10h 5m 9h 33m

Solar UV radiation in Hercules, California, United States §

Hercules experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / 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 4. For more detailed information, check out our hourly Hercules UV Index data.

Average daily maximum UV levels by month for Hercules, 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) 3 5 8 9 10 11 11 10 9 6 4 3