Rancho Cucamonga's climate is characterized by mild winters, with temperatures rarely dropping below freezing and averaging around 14°C in January. Spring brings gradual warming, with April being the warmest month of the season, often reaching highs of up to 34°C. Summer is hot, with July and August being the hottest months, frequently seeing temperatures soar above 40°C. Autumn is mild, with October being a particularly pleasant month, while winter is cool, with January and December experiencing some chilly days below 0°C.