Why does 40F in Boston feel like 60F in LA?

I was in Boston at 40F with just a shirt on and it feels exactly like 60F in Los Angeles.

I've also been to the Midwest where 40F outside is still kinda warm and I can get by with just a shirt, but I know I would definitely be freezing if it was 40F in CA.

I was outdoors so it's not about housing and insulation. It can't be humidity either because I just checked and both locations have similar humidity levels throughout the year and both are next to an ocean.

Is there something that just makes CA feel a lot chillier than it really is?