Originally Posted by
jamesdak
My speeds always drop in the winter. I attribute it to the effects of the added clothing. More weight, more wind resistance, less flexibility, etc. Pretty much an accepted norm for those of us that bike year round. Just keep going hard on the effort and it will have paid off by the time spring arrives.
+1
In addition to the above, air density increases as temperature decreases, and if I recall correctly, this increases aerodynamic drag.