I would be concerned that moisture would destroy the roller mechanism unless you find something specifically for outdoors. Keep me posted about how you solve this.

What about vertical shades? You could change out the slats if you wanted to even.
Kathy G in MI

dayenu, that's a good point about the moisture destroying the mechanism. DH has a new solution which is that we make a 'shower curtain' with grommets at the top and rings to slide along a pipe. He thinks that a metal rod run through the bottom will keep it from swinging wildly in the wind and it can be removed when the curtain is not needed, the curtain can be moved to the wall and held by a tie-back. Sound plausable?
Kathy G, in the wild wind situation, verticals would be a problem, though they would look nice.
Thanks to both for your suggestions.
josal

I have two ideas for you. First, the best one, is to line your roman shades. You would have to take the rings off the back of the shade that the strings run through. Take the shade off the headrail. Make a piece of lining using 100% polliester just slightly narrower than the shade. A small bottom and side hem is all you need to finish the edges. Lay the lining on the back of the roman shade and clothes pin them together to keep everything in place. Re-attach the rings to the shade through both the shade and lining. Re-staple the shade to the headrail and you're away laughing. The second idea is to make a roll-up shade,to hang behind your roman shade. To do this you finish a piece of fabric slightly narrower than your romans and about 8" longer. Staple the top to the top of a board so the face of the fabric goes around the narrow front of the board and over the top. The board will sit on an angle bracket on the wall when you install it just like your roman shades do. Lay the shade on a table. Roll the bottom up on a dowel,that is slightly narrower than the fabric, about 6".(a cut off broom handle will work) It can be rolled either direction. Put an eye screw about 4" away from each end of the headrail board on the under side. Now the tricky part... for a right hand pull string, staple one end of the string to the top side of the board directly opposite the eyescrew, Bring the string down the front of the shade, around the rolled up bottom and up the back to the eyescrew. Put the end of the string through that eyescrew and over to the other.Take the string through that second eyescrew and measure out about 20" of string past that eyescrew. Hold the string in place and loop it back through the second eyescrew again so you have a 20" loop past that second eyescrew. Take the string down the back of the shade, around the roll and up the front. Staple the string to the top of the board directly opposite the second eyescrew. Now you can hold the shade by the headrail, pull on the loopwhich will roll up the fabric to raise the shade. You will need a cord cleat on the wall to wrap the loop on to hold the shade up.

Oh, DIRTY KNEES IL, those are two good ideas. Alas, dh has decided on the 'shower curtain' approach and I gave the roman shades to my daughter for her garage sale. But, hey, he gets to do most of the work now! Gotta love that!

Josal, I've been thinking of something like that too. I'd even like to do two layers, one for sun blocking, and one for mosquito netting, so the shower curtain approach probably wouldn't work for me. When it's done, could you give an update & maybe a photo?

We bought that black mesh stuff,i guess it's screening stuff.It's kinda soft.Anyway we put that on the top(roof) of our patio and where we get the afternoon sun shining brightly on the west side,we just hung a piece of it,and i sewed a hem in the bottom and added a piece of metal stripping to weight it down.On the top it's stapled to the roof edge.Works for us.
Kathi