One of our customers in Québec was tired of having to shovel snow off their porch all winter. Moisture from melting snow meant that the deck required frequent maintenance and staining. Also, strong winds caused drafts inside the house. The solution to all of these problems was to protect the porch from the elements by enclosing it with a heavy duty tarp.
One down side is that the solid tarps may block your view. There are three ways that this could be overcome:
Here we see that common tie downs were used to hold the tarp in place. Another option would have been to have us put a channel (or pocket) at the bottom of the tarp into which you could slide a pole.
If you still get wind and cold air coming up from the bottom of your porch you could also consider installing Deck Skirting. If you only want to add privacy to your deck consider adding a deck railing tarp.