Redding has a hot-summer Mediterranean climate , with very hot, dry summers and cool, wet winters. Winter (October–April) provides the most precipitation of any season in Redding—the weather tends to be either rainy or foggy and at times, snow occurs. While summers are mostly hot and dry, thunderstorms are not uncommon. The average daily maximum temperature in July stays near 100 °F (37.8 °C). The highest official recorded temperature in Redding was 118 °F (48 °C) on July 20, 1988, recorded at the nearby Redding Municipal Airport and the most recent of three occasions, however some residents say they recall a high temperature of 121 in the summer of 1981 and even just recently, 126 in the summer of 2020. Redding has an average possible sunshine of 88%, the second-highest percentage (after Yuma, Arizona) of any US city.
Redding occasionally receives snow, though it has received as much as 23 inches (58 centimeters) of snow in a single storm, occurring on December 4–7, 1909 and December 22–24, 1968, including 16 in (41 cm) on December 23, 1968, the most in any calendar day on record. It rarely gets sleet or freezing rain. Frost occurs commonly in December through February, less often in March or November. In spring, rain is common. The city is located near the foothills of the Cascade and Klamath mountain ranges and it therefore gets much more rain than most places in the Sacramento Valley; temperature differentials between land and sea cause moist air from the latter to flow over the southern Sacramento valley during the summer months, producing intense heat in Redding. The direction of this winds switches from the north and east in the summer, as hot, high-pressure air flows from land to sea, making the area very dry. Tornadoes are extremely rare; flooding occurs only around the area near the Sacramento River. The coldest temperature recorded in Redding was 16 °F (−9 °C) on January 17, 2012 and December 9, 2009.