Before you do anything that may cause them any more stress, it would be helpful to know which particular roses the ones in your photos are, how old they are, etc.
Roses take a while to get established and produce decent sized blooms. If yours are newly planted (as in just this past year) you need to give them more time.I'm in the same climate zone as you and with this heat we're having mine aren't exactly at their best, either. Mine rarely produce normal sized blooms in the summer, but they do in the spring and fall when it isn't so hot.
