Hi,
I am in Austin Texas, but black spot is a big problem here as well. We learned inour master gardener class that the best thing for black spot is to buy roses that don't get it!!!

Also buy roses that do well in heat and make sure you give them good drainage - and that may mean putting them up on a small hill or in a raised bed. There are roses that have been tested by extension services called Earthkind roses. No black spot, no having to cut off the spent blooms, do well if you don't water them. Here are some web sites to learn about them and find them.
http://aggie-horticulture.tamu.edu/earthkindrose/
http://www.houstonrose.org/earthkin.htm - has a list of the best.
I have grown the rose called Belinda's Dream and recommended it to everyone. It is a gorgeous large pink shrub rose that flowers 10 months of the year, has a wonderful fragrance, and very few thorns. I planted it by my patio and love sitting there with a cup of coffe in themorning smelling the lovely fragrance. Another one not on the list that I think is better than the Knockout rose everyone was talking aobut this year is Playboy rose - another shrub rose, but a single. It is beautiful with dark green leaves and flowers all over the plant!

It also flowers all year, not much scent, does ok if you have a little shade and has few thorns. I didn't have to spray either of them all summer for blackspot whereas I had to spray my David Austin roses all summer! And they have thorns!
by the way - all roses need full sun - and rose fertilizer! There are a few that can take a little shade, but they won't flower as well. And they need water except for the Earthkind roses that still need it when they are establishing themselves. another expectation is that the rose will just sit there the first year you plant it. The second year it will really take off, so be patient.
Redbudlover