Basil in WA: Inside or Out?

I am currently in Washington State, USA, on Whidbey Island where the temperature goes down into the 50s (degrees Fahrenheit) at night low 70s to 80 (sometimes even 90 during the day).
I have some basil plants in pots. Should I bring them inside? If so, what kind of light should they have.?

Your basil plants would be happier if you were able to have them outside during the day, because they love high light and heat. Those cool nights they will not like but as long as the temperature does not go much below 50 degrees Fahrenheit (10 degrees Celsius) they will be Ok outside. Place them close to a wall so they get the shelter and heat from it. Once bringing them indoors becomes necessary put them on your sunniest window, or close to the lights in a two light flourescent light fixture.