What are the winter climate, general temperature and clothes suitable for Los Angeles, San Francisco, new york and Washington?

The climate in Los Angeles is similar to that in San Francisco, and it is warmer. (It's basically a big sun, similar to the southern coastal cities) You don't need a lot of clothes. The lowest is 10 degree. I think it's enough to bring a coat or sweater with thick clothes inside. If you travel, it is windy at the seaside, so it is recommended to bring a windbreaker or clothes with a hat.

It is much colder in new york and Washington, especially in new york. When you go out, you should have a thick coat. But if you don't stay outside for a long time, don't wear too much, because it's warm indoors, sometimes warmer than some houses in Los Angeles. I think it's necessary to wear a thick coat+sweater (if it's cold, and often stay outdoors)+short sleeves/thin shirts (inside the sweater), and people who are afraid of the cold wear long pants (personally, it's unnecessary).

American clothes are actually cheaper than those in China, so you can buy them if you don't bring them all.

If you have any questions, ask me. I have been to all these places, and now I am in new york. :)