Riverside, CA Climate & Monthly Averages
Riverside has a semi-arid climate. August is the hottest month, averaging 96° by day; January is the coldest at 65°.
Sunshine is a defining feature of Riverside's climate
The number that shapes daily life in Riverside is not the seasonal one but the daily one: afternoons run about 14°C warmer than the nights that follow them, every month of the year. August pairs highs of 96°F (35°C) with lows of 67°F (19°C); January pairs 65°F (18°C) with 44°F (7°C).
How sun, temperature and rain fit together
Sunshine averages 10.8 hours a day over the year - sunnier than 91% of the 3496 cities in our dataset, peaking in July at 13.7 hours. January bottoms out at 65°F (18°C) in daylight, 44°F (7°C) after dark. At its warmest, in August, Riverside runs to 96°F (35°C) in the afternoon and back to 67°F (19°C) by dawn. The wettest month is January (3.4 inches (87 mm) across 6 days) and the driest June.
Average highs hold at or above 30°C for 4 months of the year, June through September being the unbroken run. Days and nights are about 14°C apart on average - wider than almost anywhere else we cover. Relative humidity averages 56% across the year, drier than all but 10% of the 3496 cities in our dataset. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 116°F (47°C) and the lowest daily minimum 28°F (-2°C).
More climate facts for Riverside
- Hottest month: August - highs near 96°F (35°C)
- Coldest month: January - highs near 65°F (18°C)
- Decade extremes (2015-2024): 116°F (47°C) high · 28°F (-2°C) low
- Wettest month: January (6 rainy days) · Sunniest: July (13.7 h sun/day)
- Climate type: semi-arid
- Annual swing: 14°C between the average warmest and coolest month · day to night: 14°C
- Months averaging 30°C or hotter: 4
- Average humidity: 56%
The most comfortable sunny-weather window
Best time to visit Riverside
January to May and November is the sweet spot for Riverside - temperatures sit either side of the peak heat rather than in it. Expect 72°F (22°C) in the afternoon and around 5 days of rain in a typical month of it. For the same question asked the other way round, see where else is warm in January.
What to pack
Pack for Riverside with lightweight, breathable clothing and serious sun protection and a mid-layer for the evenings, which fall away fast after sunset. August nights average 67°F (19°C), so evenings rarely match the afternoons.
Monthly climate table
| Month | High | Low | Rain days | Precipitation | Sunshine | Daylight | Wet-day chance | Humidity |
|---|---|---|---|---|---|---|---|---|
| January | 65° | 44° | 6 | 3.4 in | 8.3 h/day | 10.1 h | 20% | 63% |
| February | 68° | 45° | 6 | 2.6 in | 9.0 h/day | 10.9 h | 21% | 58% |
| March | 70° | 47° | 8 | 2.7 in | 10.2 h/day | 11.9 h | 25% | 64% |
| April | 77° | 52° | 3 | 0.8 in | 11.3 h/day | 13.0 h | 9% | 57% |
| May | 79° | 54° | 3 | 0.5 in | 12.0 h/day | 13.9 h | 10% | 62% |
| June | 89° | 60° | 0 | 0.0 in | 13.3 h/day | 14.4 h | 1% | 55% |
| July | 95° | 65° | 0 | 0.2 in | 13.7 h/day | 14.2 h | 2% | 52% |
| August | 96° | 67° | 1 | 0.2 in | 12.7 h/day | 13.4 h | 2% | 51% |
| September | 92° | 64° | 2 | 0.4 in | 11.3 h/day | 12.3 h | 7% | 53% |
| October | 84° | 58° | 2 | 0.6 in | 10.3 h/day | 11.3 h | 8% | 49% |
| November | 74° | 49° | 3 | 1.0 in | 9.4 h/day | 10.3 h | 11% | 46% |
| December | 66° | 44° | 5 | 2.4 in | 8.2 h/day | 9.9 h | 17% | 56% |
Riverside month by month
Each card shows the average high and low. The bar places that month between Riverside's coldest night and warmest afternoon.
January
- Rain
- 6 days
- Sunshine
- 8.3 h
- Daylight
- 10.1 h
February
- Rain
- 6 days
- Sunshine
- 9.0 h
- Daylight
- 10.9 h
March
- Rain
- 8 days
- Sunshine
- 10.2 h
- Daylight
- 11.9 h
April
- Rain
- 3 days
- Sunshine
- 11.3 h
- Daylight
- 13.0 h
May
- Rain
- 3 days
- Sunshine
- 12.0 h
- Daylight
- 13.9 h
June
- Rain
- 0 days
- Sunshine
- 13.3 h
- Daylight
- 14.4 h
July
- Rain
- 0 days
- Sunshine
- 13.7 h
- Daylight
- 14.2 h
August
- Rain
- 1 day
- Sunshine
- 12.7 h
- Daylight
- 13.4 h
September
- Rain
- 2 days
- Sunshine
- 11.3 h
- Daylight
- 12.3 h
October
- Rain
- 2 days
- Sunshine
- 10.3 h
- Daylight
- 11.3 h
November
- Rain
- 3 days
- Sunshine
- 9.4 h
- Daylight
- 10.3 h
December
- Rain
- 5 days
- Sunshine
- 8.2 h
- Daylight
- 9.9 h
Looking for warmer alternatives? Browse warm places by month, or compare Riverside's coolest part of the year: January, December, February.
Seasonal weather under Riverside's sunnier skies
Spring (March through May)
Through spring, Riverside is pleasantly warm: 75°F (24°C) by day, 51°F (11°C) after dark, and rain comes on about 14 days over the three months. Daylight is generous - around 11.2 hours of sun a day.
Summer (June through August)
Summer in Riverside runs at full heat, with daytime highs averaging 93°F (34°C) and nights around 64°F (18°C); precipitation is sparse, near 11 mm (0.4 in) for the season. Daylight is generous - around 13.2 hours of sun a day.
Fall (September through November)
Through fall, Riverside brings hot afternoons: 83°F (29°C) by day, 57°F (14°C) after dark, and precipitation is sparse, near 2.0 inches (51 mm) for the season. Daylight is generous - around 10.3 hours of sun a day.
Winter (December through February)
Winter in Riverside stays on the cool side of mild, with daytime highs averaging 66°F (19°C) and nights around 44°F (7°C); rain comes on about 17 days over the three months.
How unusual is Riverside?
- Rain or snow reaches the ground on 40 days a year - fewer wet days than all but 6% of the 3496 cities we track.
- 59% of the year's precipitation falls in its wettest three months - more seasonal than 91% of the 3496 cities we track.
- Annual precipitation is 14.7 inches (374 mm) - drier than all but 10% of the 3496 cities we track.
These comparisons use the same ten-year window for every city in the dataset.
Riverside temperature extremes in the 2015–2024 dataset
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ. Need another precipitation unit? Use the rainfall converter.