Altadena is a city of approximately 42,800 people in California, United States. Located in the Pacific Time Zone at 34.2°N latitude.
In 2025, Altadena recorded an average annual temperature of 64°F — about 1.0°F below the 30-year normal of 65°F. The hottest day reached 100°F in August; the coldest was 35°F in March. Total precipitation was 32 inches (wetter than usual). The wettest month was November.
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