Rancho Cucamonga Climate by Month
Rancho Cucamonga, California, United States
Hot summers and mild winters, with little rain, mostly from December to March.
The climate in Rancho Cucamonga is one of hot summers and mild winters, with little rain, mostly from December to March. August is the warmest month, with highs around 93°F (34°C); December is the coolest at 67°F (20°C), and nights dip to 41°F (5°C). It gets only 13 in (336 mm) of rain a year. May to September are almost completely dry.
- Warmest month
- 93°F(34°C)
- Average high, August
- Coldest nights
- 41°F(5°C)
- Average low, December
- Rain per year
- 13 in(336 mm)
- Wettest: February
- Humidity
- 46%
- Sunniest: June
Best and worst months in Rancho Cucamonga
Best for weatherThe most comfortable weather comes in April, May and November, with highs around 76°F (25°C) and about 0.8 in (21 mm) of rain a month.
Least pleasantJuly and August are the least pleasant; August is the hottest, with highs of 93°F (34°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in April.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Rancho Cucamonga weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 68°F(20°C) | 43°F(6°C) | 2.7 in(69 mm) | 47% | 2.9 |
| FebFebruary | 68°F(20°C) | 43°F(6°C) | 3.0 in(77 mm) | 46% | 3.4 |
| MarMarch | 71°F(22°C) | 46°F(8°C) | 2.0 in(51 mm) | 54% | 4.9 |
| AprAprilBest | 76°F(24°C) | 48°F(9°C) | 1.1 in(28 mm) | 47% | 6.0 |
| MayMayBest | 79°F(26°C) | 53°F(12°C) | 0.3 in(8 mm) | 50% | 6.5 |
| JunJune | 85°F(30°C) | 57°F(14°C) | 0.0 in(1 mm) | 50% | 7.1 |
| JulJuly | 91°F(33°C) | 61°F(16°C) | 0.0 in(1 mm) | 45% | 7.0 |
| AugAugust | 93°F(34°C) | 63°F(17°C) | 0.1 in(2 mm) | 43% | 6.7 |
| SepSeptember | 90°F(32°C) | 60°F(16°C) | 0.2 in(5 mm) | 44% | 5.6 |
| OctOctober | 82°F(28°C) | 54°F(12°C) | 0.4 in(11 mm) | 43% | 4.3 |
| NovNovemberBest | 74°F(24°C) | 46°F(8°C) | 1.1 in(27 mm) | 39% | 3.3 |
| DecDecember | 67°F(20°C) | 41°F(5°C) | 2.2 in(56 mm) | 42% | 2.7 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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