Hope you have success with the LED's.

No need for hope, I can tell you for sure they work.

how far are the plants from the window ? they look fairly close and I'm thinking that its not light you would have a problem with, but temperature ?
Also - wouldn't reduced light be "natural" at this time of year and thus allow the plants to go into semi-dormancy ? Mine are also in SF windows and I don't supplement light at all....though we do get more than 4hrs of daylight !