Rancho Cucamonga (CA) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Rancho Cucamonga, California, United States of America. The figures are based on a 30-year period (1990–2020) to provide a reliable average. Now, let's break down all the details for a clearer picture.

Rancho Cucamonga's climate is marked by below-average rainfall, accumulating 318 mm (13 in) of precipitation yearly. The distribution includes a distinct dry season during certain months as shown in the precipitation charts below.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

The seasons in Rancho Cucamonga, bring significant changes in precipitation. The wettest month, December, receives moderate rainfall, with an average of 98 mm (3.9 in) of precipitation. This rainfall is distributed across 8 rainy days.

In contrast, the driest month, June, experiences much less rainfall, totaling 0.2 mm (0.01 in) over 0 rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

December, the wettest month, has a maximum daytime temperature of 18°C (64°F). The city receives 205 hours of sunshine in this period. During the driest month June you can expect a temperature of 30°C (86°F). For more detailed insights into the city's temperatures, visit our Rancho Cucamonga Temperature page.

Rancho Cucamonga's average annual precipitation is 318 mm (13 in). Let's compare this to some popular worldwide tourist destinations:

The city of Rome, Italy, has an average annual precipitation of 832 mm (33 in), spread fairly evenly throughout the year.

In Shanghai, China, the annual average precipitation is 1347 mm (53 in), with a humid subtropical climate.

In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.

Singapore, situated near the equator, gets 2581 mm (102 in) of rainfall annually, with no distinct dry season and consistent monthly precipitation.

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Climate change is affecting precipitation patterns worldwide, including Rancho Cucamonga (CA):

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm (15 inches) wide and 20 cm (7.9 inches) thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA, over 31.5 meters (103 feet) fell during the winter of 1972.

For more detailed information about Rancho Cucamonga (CA)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Rancho Cucamonga (CA) Climate page.