If you have reduced sail to the smallest set up you can, and you still want to reduce sped, you will have to resort to other tactics.
For example, if sailing close hauled, pinch up into the wind higher and she will loose speed.
Down wind, sheet in the sails or the opposite of what you should be doing. Beam reaching ease until you are spilling some. All of this after you have reduced sail area.
Wind speed is wind speed no matter how heavy or cold. Hey, I am not a weather man, just my thoughts.
I guess I have to edit my post, Faster has charts to prove it