Thank you! I relate; I live in Montréal, close to New England, with similar climate. The current UV Index for Montréal is... 0. And the current UV Index for Boston is... 0.6. (1.6 later today)
I can't find a rigorous academic source right now, but the top web results all say we need at least UV Index 3 for our skin to be able to make enough Vitamin D. I guess summer may work for us, in the Montreal/New England area, but other than that, yeah, you and I will need to get Vitamin D from diet and/or supplements. And fish is expensive, so supplements it is.
I can't find a rigorous academic source right now, but the top web results all say we need at least UV Index 3 for our skin to be able to make enough Vitamin D. I guess summer may work for us, in the Montreal/New England area, but other than that, yeah, you and I will need to get Vitamin D from diet and/or supplements. And fish is expensive, so supplements it is.