Honeymoon – coldest options?

I’m a teacher, my fiancé is an engineer. Unfortunately with my schedule, we really can only do our honeymoon in the summer months or right over the winter holidays. My fiancé struggles in the heat, what are some of our best potential options?

For reference, we’ll be flying out of the DC area. We don’t want to go to Asia because we know the heat won’t be tolerable. I’ve personally been to Switzerland (during Christmas, my favorite trip ever) Iceland (in December) Copenhagen (April). Together we’ve been around the US, Brazil, and Canada. We’re open to suggestions as we’re just in the planning phrase right now!