Los Angeles Basin, where the Los Angeles metropolitan area is located, according to The Köppen climate classification, has a Mediterranean climate, a type of dry subtropical climate. It is characterized by dry summers and rainy winters. The rainfall is heavily seasonal, ranging from 3.25 inches of rain in February, to 0.03 inches in July.
The average low temperature follows a similar pattern. It rarely goes below 50 F, except in December (48.7 F) and January (48.8 F). The lowest ever temperature was 28 F, measured on three separate occasions – Feb. 3, 1883, Jan. 7, 1913 and Jan. 4, 1949.
During summers (from Jun to September), the night temperature in Los Angeles doesn’t get below 60 F, meaning even at its coldest, the nights are still rather pleasant.
There are several reasons why the temperature never really goes down, even in during the winter nights, in Los Angeles. The biggest is the proximity to the ocean. Pacific acts as a giant heat sink, gathering heat during the day and releasing it during the night. The warm air gets blown over the city, keeping the temperature from plummeting.
The second reason is the El Nino phenomenon. The warm-phase of an El Niño–Southern Oscillation usually coincides with winter months and raises the temperature significantly during this phase, keeping Los Angeles nights warm.
So, the answer to the question does LA gets cold at night is no, not really. There may be some winter nights when it can get unpleasant, but even then, it is far from unbearable. This is the main reason why Los Angeles has the second highest homeless population in the nation, behind New York. Almost 50,000 homeless people were living in Los Angeles in 2018, and the main reason they choose LA was its mild climate, making it easier to find a place to sleep during the night.