Rancho Cucamonga, California climate: NOAA's gridded normals for the city, beside the nearest station records
NOAA's gridded 1991-2020 normals put Rancho Cucamonga's center at January lows of 44°F and July highs of 93°F, a yearly mean of 65.2°F and 20.0 inches of precipitation. No NOAA station keeps a record under the city's name. The nearest station record, Ontario (5 miles S, 949 ft), has January lows of 45°F and July highs of 94°F.
176,675 people (Census Bureau 2024). Distances and directions are from the city's center.
- Jan 66° 44°
- Feb 66° 44°
- Mar 70° 47°
- Apr 74° 49°
- May 78° 53°
- Jun 86° 58°
- Jul 93° 63°
- Aug 94° 64°
- Sep 90° 61°
- Oct 82° 55°
- Nov 73° 48°
- Dec 65° 43°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
The months above are NOAA's gridded normals at Rancho Cucamonga's center.
What is each month like in Rancho Cucamonga?
NOAA's grid estimates the normals every 5 km or so from the stations around each point, terrain included. It smooths between stations, so night lows at the heart of a large city can run warmer than the grid shows: at five big-city airports we compared, the grid's highs were within about 1°F of the station and its lows 1-6°F cooler. The nearest record's high and low are beside each month.
| Month | High | Low | Mean | Precip. | Ontario high | Ontario low |
|---|---|---|---|---|---|---|
| January | 66°F | 44°F | 54.8°F | 4.50 | 68°F | 45°F |
| February | 66°F | 44°F | 55.3°F | 4.77 | 68°F | 46°F |
| March | 70°F | 47°F | 58.3°F | 3.13 | 72°F | 49°F |
| April | 74°F | 49°F | 61.4°F | 1.08 | 76°F | 51°F |
| May | 78°F | 53°F | 65.6°F | 0.54 | 80°F | 56°F |
| June | 86°F | 58°F | 71.8°F | 0.08 | 86°F | 60°F |
| July | 93°F | 63°F | 77.8°F | 0.06 | 94°F | 65°F |
| August | 94°F | 64°F | 79.2°F | 0.03 | 95°F | 65°F |
| September | 90°F | 61°F | 75.9°F | 0.15 | 91°F | 64°F |
| October | 82°F | 55°F | 68.3°F | 0.84 | 83°F | 57°F |
| November | 73°F | 48°F | 60.3°F | 1.37 | 75°F | 49°F |
| December | 65°F | 43°F | 53.8°F | 3.47 | 67°F | 44°F |
In metric: a yearly mean of 18.4°C, January lows of 7°C, July highs of 34°C and 509 mm of precipitation a year.
Source: NOAA NCEI U.S. Monthly Gridded Climate Normals 1991-2020 (nClimGrid, accession 0245564); NOAA NCEI 1991-2020 station normals. The grid cell holding the city's Census center point.
What do the station records around Rancho Cucamonga say?
Each row is a NOAA station's own 1991-2020 normals, with the snow and frost dates the grid does not give. A record downhill or nearer the coast than the city can run warmer, one uphill cooler: compare the elevations.
| Record | Where | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| OntarioOntario International Airport | 5 mi S | 949 ft | 66.8°F | 45°F | 94°F | 11.6 | – | January 4 |
| ChinoChino Airport | 11 mi S | 650 ft | 66.1°F | 42°F | 94°F | 10.0 | – | January 17 |
| PomonaPomona/Fairplex | 12 mi W | 999 ft | 65.0°F | 43°F | 90°F | 14.5 | 0 | January 8 |
Source: NOAA NCEI 1991-2020 U.S. Climate Normals; place center and population: Census Bureau 2024. Last frost: the median last spring date of 32°F.
How much snow, how late a frost, what zone and how much sun in Rancho Cucamonga?
NOAA's grid gives no snow, frost dates or records, so these come from the nearest station record, Ontario (5 miles S, 949 ft). NOAA publishes no snowfall normal for it; the nearest record that has one, Pomona (12 miles W), gets 0 inches a year. The last spring frost (32°F) comes after January 4 in half of years and the first autumn frost before December 30. Its record high is 118°F (2020) and its record low 25°F (2007) (kept since 1998).
The USDA's 2023 Plant Hardiness Zone Map puts Rancho Cucamonga in zone 10a across its 4 ZIP code areas.
Over a year 92% of the sunlight that would reach the ground under clear skies gets through the clouds in the area (5.8 kWh per square metre a day, NASA POWER 2001-2020); August is the sunniest month (96%) and December the cloudiest (85%).
Ontario's page has its months, frost probabilities, records by month and recent years. NOAA's grid has monthly figures only, so there are no day-by-day month pages for Rancho Cucamonga; the nearest record's month pages have them.
Source: NOAA NCEI 1991-2020 normals, station USW00003102; records: ACIS; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; sunshine: NASA POWER.
How does the climate vary across Rancho Cucamonga, ZIP code by ZIP code?
4 ZIP code areas lie wholly or partly in Rancho Cucamonga. On NOAA's grid 91701 is the warmest (65.3°F a year) and 91739 the coolest (65.0°F), so the city is nearly uniform. Each row also names the nearest station record and its frost dates.
| ZIP code | Zone | Year | Jan low | Jul high | Precip. | Nearest record | Last frost | First frost |
|---|---|---|---|---|---|---|---|---|
| 91701 | 10a | 65.3°F | 44°F | 93°F | 19.8 | Ontario (6 mi) | January 4 | December 30 |
| 91730 | 10a | 65.3°F | 43°F | 93°F | 17.4 | Ontario (3 mi) | January 4 | December 30 |
| 91737 | 10a | 65.2°F | 44°F | 93°F | 20.0 | Ontario (7 mi) | January 4 | December 30 |
| 91739 | 10a | 65.0°F | 43°F | 93°F | 19.5 | Ontario (8 mi) | January 4 | December 30 |
Source: Census Bureau 2020 ZCTA-to-place relationship file and ZCTA centers; NOAA NCEI gridded and station normals, 1991-2020. A ZIP area counts when at least a tenth of its land (and 0.5 km²) is in the city; its figures are the grid cell at its center; frost dates are the nearest record's medians of 32°F.