Agreed with the previous posts: Find yourself a heated wand wash car wash, and take it there very early in the morning or late at night when it's not busy. Take the time to do a good two bucket wash job, including door jambs etc, and then dry it off with some high quality MF cloths. As for the wax/sealant; you'll either need a heated garage, or get it professionally done until you can lay hands on it yourself in the spring.
2015 Porsche Macan S
2011 E90 M3 Alpine White on Fox Red
2007 E90 335I Graphite on Terra