It can be shorts weather in Jan./Feb. or it can be rainy and cold.
Most visitors don't realize how chilly it gets in SoCal once the sun goes down. The warmth of the sun may allow shorts during the day, but warmer clothing is generally desired once it goes down. Visitors arriving from freezing conditions generally perceive the coolness to be mild at first, but after a day or so, their body adjusts and they realize it's cold.
