Riverside, California climate: Normal weather by month, frost dates and records
Riverside's normal year runs from 43°F December nights to 95°F August afternoons, with 9.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 19.0°C, December lows of 6°C, August highs of 35°C, 238 mm of precipitation a year.
- NOAA stationRiverside Municipal Airport
- Station IDUSW00003171
- Location33.95°N 117.44°W
- Elevation805 ft (245 m)
- From the center3 miles
- Population323,757
On October 23, the normal high in Riverside is 81°F and the normal low 54°F, and the chance of measurable rain or snow is 9%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Riverside.
- Jan 68° 44°
- Feb 68° 45°
- Mar 72° 47°
- Apr 76° 50°
- May 80° 55°
- Jun 87° 59°
- Jul 93° 64°
- Aug 95° 65°
- Sep 91° 62°
- Oct 83° 55°
- Nov 75° 47°
- Dec 67° 43°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Riverside each month?
August is the warmest month, with normal highs of 95°F; December the coldest, with normal lows of 43°F. The most precipitation falls in February (2.41 in), the least in June (0.01 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 68°F | 44°F | 55.6°F | 2.29 | 5 | <1 | 1 | 10 h 10 min |
| February | 68°F | 45°F | 56.3°F | 2.41 | 7 | <1 | 1 | 11 h |
| March | 72°F | 47°F | 59.5°F | 1.21 | 5 | 1 | <1 | 11 h 50 min |
| April | 76°F | 50°F | 62.9°F | 0.59 | 4 | 3 | <1 | 13 h |
| May | 80°F | 55°F | 67.6°F | 0.20 | 2 | 6 | <1 | 13 h 50 min |
| June | 87°F | 59°F | 73.0°F | 0.01 | <1 | 12 | <1 | 14 h 20 min |
| July | 93°F | 64°F | 78.6°F | 0.12 | 1 | 24 | <1 | 14 h 10 min |
| August | 95°F | 65°F | 79.8°F | 0.02 | 1 | 25 | <1 | 13 h 30 min |
| September | 91°F | 62°F | 76.6°F | 0.11 | 1 | 19 | <1 | 12 h 30 min |
| October | 83°F | 55°F | 68.9°F | 0.33 | 2 | 9 | <1 | 11 h 20 min |
| November | 75°F | 47°F | 61.0°F | 0.57 | 4 | 2 | <1 | 10 h 30 min |
| December | 67°F | 43°F | 54.8°F | 1.51 | 5 | <1 | 1 | 9 h 50 min |
| Year (annual) | 80°F | 53°F | 66.2°F | 9.37 | 35 | 101 | 4 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 20°C | 6°C | 13.1°C | 58 mm |
| February | 20°C | 7°C | 13.5°C | 61 mm |
| March | 22°C | 8°C | 15.3°C | 31 mm |
| April | 24°C | 10°C | 17.2°C | 15 mm |
| May | 27°C | 13°C | 19.8°C | 5 mm |
| June | 30°C | 15°C | 22.8°C | 0 mm |
| July | 34°C | 18°C | 25.9°C | 3 mm |
| August | 35°C | 18°C | 26.6°C | 1 mm |
| September | 33°C | 17°C | 24.8°C | 3 mm |
| October | 28°C | 13°C | 20.5°C | 8 mm |
| November | 24°C | 9°C | 16.1°C | 14 mm |
| December | 19°C | 6°C | 12.7°C | 38 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003171; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Riverside?
Normal highs sit between 65°F and 85°F in January, February, March, April, May, October, November and December. Of those, May has the fewest days with rain (2).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003171.
When is the last frost in Riverside?
In Riverside, the last spring frost (32°F) comes after January 9 in half of years and after February 21 in one year in ten; the first autumn frost comes before December 30 in half of years and before December 5 in one year in ten. A night at 32°F or colder comes at all in 58% of years here (NOAA).
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- January 91 year in 10 after February 21; 9 in 10 after December 16
- First autumn frost, half of years before
- December 301 year in 10 before December 5; 9 in 10 before February 6
NOAA puts the median frost-free season at 362 days, and the season without a hard freeze (28°F) at 365 days.
The USDA's 2023 Plant Hardiness Zone Map puts Riverside in zones 9b to 10a across its 8 ZIP code areas (10a in 92507, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Riverside's NOAA station is in zone 10a: the coldest night of a typical year reaches 31°F (19 complete years).
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00003171; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Riverside ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Riverside's 8 ZIP code areas run from zone 9b to 10a: 7 in 10a and 1 in 9b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Riverside?
In a normal year in Riverside, 101 days a year reach 90°F (22 of them 100°F or more), 4 nights fall to 32°F or colder and 35 days bring measurable precipitation.
- Days at 90°F or more
- 101a normal year
- Days at 100°F or more
- 22a normal year
- Nights at 32°F or colder
- 4a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 35a normal year
The highest temperature in Riverside's official record (kept by the National Weather Service since 1893) is 118°F, on June 16, 1917; the lowest is 19°F, on January 7, 1950.
The wettest calendar year on that record is 1983, with 22.94 in; the snowiest season is 1948–49, with 3.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00003171; records: ACIS (NOAA Regional Climate Centers), NWS threaded record RALthr. Records use complete months only; a month missing more than three days is left out.
How sunny is Riverside?
Over a year 87% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Riverside, 5.4 kWh per square metre a day. August is the sunniest month (92%) and February the cloudiest (83%). Among the 459 U.S. places of 50,000 or more, that ranks tied 58th (with 22 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 85% | 3.3 |
| February | 83% | 4.1 |
| March | 85% | 5.4 |
| April | 86% | 6.5 |
| May | 83% | 6.9 |
| June | 85% | 7.3 |
| July | 89% | 7.4 |
| August | 92% | 7.0 |
| September | 91% | 6.0 |
| October | 88% | 4.6 |
| November | 87% | 3.6 |
| December | 83% | 2.9 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Riverside need?
A normal year in Riverside brings 1,386 heating degree days, 74% fewer than the median U.S. place (5,373), and 1,854 cooling degree days, 2.0 times the median (908). One month needs 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 5,993 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 296 | 6 |
| February | 251 | 7 |
| March | 189 | 18 |
| April | 110 | 48 |
| May | 33 | 114 |
| June | 2 | 242 |
| July | 0 | 422 |
| August | 0 | 459 |
| September | 2 | 349 |
| October | 31 | 154 |
| November | 155 | 33 |
| December | 318 | 2 |
| Year (annual) | 1,386 | 1,854 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003171. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Riverside been warmer than normal lately?
2025 averaged 67.3°F, 1.1°F above the 1991-2020 normal of 66.2°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 66.9°F | +0.7°F | 7.26 |
| 2022 | 68.1°F | +1.9°F | 4.49 |
| 2023 | 65.2°F | −1.0°F | 13.19 |
| 2024 | 66.6°F | +0.4°F | 11.31 |
| 2025 | 67.3°F | +1.1°F | 8.66 |
Source: observed years: ACIS, station USW00003171. A year counts only with all twelve months complete.
How does Riverside's climate compare?
Riverside is warmer than 200 of the other 218 places with their own NOAA record in California, and wetter than 37. Across the 7,247 U.S. stations with normals, its annual mean of 66.2°F is warmer than 90%.
In the Köppen classification computed from these normals, Riverside is BSh: hot semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Riverside share this climate record?
9 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Jurupa Valley, CAalso near: Ontario (8 mi, 66.8°F a year); Chino (10 mi, 66.1°F a year)108,154 people · 4 mi NW
- Rialto, CAalso near: Redlands (12 mi, 65.2°F a year); Ontario (13 mi, 66.8°F a year)104,918 people · 12 mi N
- Bloomington, CA24,324 people · 8 mi N
- Woodcrest, CA17,111 people · 6 mi SE
- El Sobrante, CA13,206 people · 6 mi S
- Home Gardens, CA11,430 people · 7 mi SW
- Lake Mathews, CA6,749 people · 10 mi SE
- El Cerrito, CA5,121 people · 9 mi SW
- March ARB, CA1,251 people · 10 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Riverside's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near Riverside. This page uses Riverside Municipal Airport; the others differ by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Riverside Citrus Experiment USC00047473 | 3 mi NE | 986 ft | 66.6°F | 44°F | 94°F | 9.9 | 0 | January 10 |
| Riverside Fire Station 3 USC00047470 | 1 mi N | 840 ft | 66.9°F | 43°F | 95°F | 10.0 | 0 | January 9 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Riverside's climate
What is the coldest month in Riverside?
December, with a normal high of 67°F and a normal low of 43°F. The warmest is August (95°F by day, 65°F at night).
Does it snow in Riverside?
Rarely. NOAA publishes no 1991-2020 snowfall normal for Riverside's NOAA station; Riverside's own co-op station Riverside Fire Station 3 records 0 inches of snow in a normal year.
What is the rainiest month in Riverside?
February, with 2.41 in of precipitation in a normal year; the driest is June with 0.01 in.
What plant hardiness zone is Riverside in?
The USDA's 2023 map puts Riverside in zones 9b to 10a across its 8 ZIP code areas (10a in 92507, the largest). By the same method at Riverside's NOAA station, the coldest night of a typical year reaches 31°F (19 years, 1991-2020): zone 10a.
How late can frost come in Riverside?
In half of years the last 32°F night comes after January 9; in one year in ten it comes after February 21. Waiting until February 21 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Riverside in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Chino, CA11 miles from this station, 66.1°F a year
- Ontario, CA12 miles from this station, 66.8°F a year
- Redlands, CA15 miles from this station, 65.2°F a year
- Lake Elsinore, CA19 miles from this station, 66.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made