Rancho Cucamonga, CA Weather by Month and Climate Averages

Rancho Cucamonga, CA gets 11.6 in of precipitation a year over about 35 rainy days. August is the warmest month (average high 94°F) and December the coldest (average low 43°F).

Rancho Cucamonga climate at a glance

Semi-arid climate

Rancho Cucamonga, CA has hot summers and mild winters. Daytime highs range from about 67°F in December to 94°F in August. February is usually the wettest month. The most comfortable time to visit is typically January, March to May, and November to December, when daytime highs sit near 72°F.

How much rain does Rancho Cucamonga get?

Rancho Cucamonga gets 11.6 in of precipitation in an average year, spread over about 35 days with measurable rain. That is fewer rainy days than 90% of the US.

February is the wettest month, with 3.1 in. June is the driest, with 0.0 in. February has the most rainy days, about 6.

The longest dry spell in the last five years lasted 175 days, to October 27, 2024.

See where Rancho Cucamonga ranks: rainiest cities in the US, US cities with the most rainy days, rainiest cities in California.

Rancho Cucamonga weather by month

Rancho Cucamonga weather in January

In January, Rancho Cucamonga averages a high of 68°F and a low of 44°F. It gets 2.6 in of precipitation over about 5 rainy days. The sun is out about 53% of daylight hours. The January record high is 90°F (2003) and the record low is 25°F (2007). January is one of the most comfortable months to visit.

Rancho Cucamonga weather in February

In February, Rancho Cucamonga averages a high of 67°F and a low of 45°F. It gets 3.1 in of precipitation over about 6 rainy days. The sun is out about 60% of daylight hours. The February record high is 91°F (2026) and the record low is 29°F (2018).

Rancho Cucamonga weather in March

In March, Rancho Cucamonga averages a high of 71°F and a low of 48°F. It gets 1.6 in of precipitation over about 5 rainy days. The sun is out about 46% of daylight hours. The March record high is 100°F (2026) and the record low is 33°F (2023). March is one of the most comfortable months to visit.

Rancho Cucamonga weather in April

In April, Rancho Cucamonga averages a high of 75°F and a low of 51°F. It gets 0.8 in of precipitation over about 4 rainy days. The sun is out about 58% of daylight hours. The April record high is 101°F (2004) and the record low is 33°F (1999). April is one of the most comfortable months to visit.

Rancho Cucamonga weather in May

In May, Rancho Cucamonga averages a high of 79°F and a low of 56°F. It gets 0.3 in of precipitation over about 2 rainy days. The sun is out about 63% of daylight hours. The May record high is 103°F (2004) and the record low is 42°F (1999). May is one of the most comfortable months to visit.

Rancho Cucamonga weather in June

In June, Rancho Cucamonga averages a high of 86°F and a low of 60°F. It gets 0.0 in of precipitation over about 0 rainy days. The sun is out about 73% of daylight hours. The June record high is 112°F (2016) and the record low is 46°F (1999).

Rancho Cucamonga weather in July

In July, Rancho Cucamonga averages a high of 93°F and a low of 65°F. It gets 0.1 in of precipitation over about 1 rainy days. The sun is out about 85% of daylight hours. The July record high is 117°F (2018) and the record low is 56°F (2004).

Rancho Cucamonga weather in August

In August, Rancho Cucamonga averages a high of 94°F and a low of 65°F. It gets 0.0 in of precipitation over about 0 rainy days. The sun is out about 83% of daylight hours. The August record high is 112°F (2017) and the record low is 56°F (1999).

Rancho Cucamonga weather in September

In September, Rancho Cucamonga averages a high of 91°F and a low of 63°F. It gets 0.1 in of precipitation over about 1 rainy days. The sun is out about 78% of daylight hours. The September record high is 118°F (2020) and the record low is 51°F (2013).

Rancho Cucamonga weather in October

In October, Rancho Cucamonga averages a high of 82°F and a low of 57°F. It gets 0.4 in of precipitation over about 2 rainy days. The sun is out about 74% of daylight hours. The October record high is 107°F (2012) and the record low is 41°F (2019).

Rancho Cucamonga weather in November

In November, Rancho Cucamonga averages a high of 74°F and a low of 49°F. It gets 0.8 in of precipitation over about 4 rainy days. The sun is out about 68% of daylight hours. The November record high is 98°F (2010) and the record low is 32°F (2015). November is one of the most comfortable months to visit.

Rancho Cucamonga weather in December

In December, Rancho Cucamonga averages a high of 67°F and a low of 43°F. It gets 1.9 in of precipitation over about 6 rainy days. The sun is out about 51% of daylight hours. The December record high is 87°F (2021) and the record low is 28°F (1998). December is one of the most comfortable months to visit.

Sunshine, humidity and wind in Rancho Cucamonga

July is the sunniest month in Rancho Cucamonga, with sunshine about 85% of daylight hours. March is the cloudiest, at 46%. Over the year the sun shines about 66% of daylight hours. Rancho Cucamonga is sunnier than 93% of the US.

Humidity peaks in March at 58% and is lowest in November at 37%.

Wind averages 6 mph over the year, and May is the windiest month at 7 mph.

Rancho Cucamonga has about 92 days a year above 90°F. Rancho Cucamonga is hotter than 90% of the US.

Thunderstorms occur on about 6 days a year.

See where Rancho Cucamonga ranks: sunniest cities in the US, cloudiest cities in the US, hottest cities in the US.

Rancho Cucamonga weather records

The hottest temperature on record at the Rancho Cucamonga station is 118°F, on September 5, 2020. The coldest is 25°F, on January 14, 2007.

The wettest day on record brought 3.6 in of rain, on February 5, 2024.

The best time to visit Rancho Cucamonga

The most comfortable time to visit is typically January, March to May, and November to December, when daytime highs sit near 72°F.

Winter (December–February) is mild, with average highs around 67°F and lows near 44°F.

Spring (March–May) is warm, with average highs around 75°F and lows near 52°F.

Summer (June–August) is hot, with average highs around 91°F and lows near 63°F.

Autumn (September–November) is hot, with average highs around 82°F and lows near 56°F.

Monthly climate

MonthPrecipRain daysWindHumiditySunshineSea tempRecord highRecord low
January2.6 in55 mph52%53%60°90°25°
February3.1 in65 mph44%60%59°91°29°
March1.6 in56 mph58%46%59°100°33°
April0.76 in47 mph56%58%60°101°33°
May0.30 in27 mph58%63%63°103°42°
June0.02 in07 mph51%73%65°112°46°
July0.05 in17 mph45%85%68°117°56°
August0.03 in06 mph45%83%70°112°56°
September0.10 in16 mph46%78%70°118°51°
October0.41 in25 mph41%74%67°107°41°
November0.80 in45 mph37%68%63°98°32°
December1.9 in65 mph47%51%61°87°28°

From ERA5 reanalysis. Sunshine is estimated from cloud cover.

Rancho Cucamonga climate questions

How much rain does Rancho Cucamonga get?

Rancho Cucamonga gets 11.6 in of precipitation in an average year, over about 35 rainy days.

What is the wettest month in Rancho Cucamonga?

February is the wettest month in Rancho Cucamonga, with 3.1 in. June is the driest, with 0.0 in.

How many rainy days does Rancho Cucamonga have a year?

Rancho Cucamonga has about 35 days with measurable rain in an average year. February has the most, about 6.

What is the hottest month in Rancho Cucamonga?

August is the warmest month in Rancho Cucamonga, with an average high of 94°F.

What is the coldest month in Rancho Cucamonga?

December is the coldest month in Rancho Cucamonga, with an average low of 43°F.

What is the record high temperature in Rancho Cucamonga?

The record high at the Rancho Cucamonga station is 118°F, set on September 5, 2020. The record low is 25°F, on January 14, 2007.

What is the sunniest month in Rancho Cucamonga?

July is the sunniest month in Rancho Cucamonga, with sunshine about 85% of daylight hours. March is the cloudiest.

What is the best time to visit Rancho Cucamonga?

The most comfortable time to visit is typically January, March to May, and November to December, when daytime highs sit near 72°F.

Source: NOAA GHCN-Daily station ONTARIO INTL AP (6 km away).

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Normals from NOAA GHCN-Daily station ONTARIO INTL AP.