i hear rattlesnake is a heat tolerant bean. i haven't grown it yet myself, but plant to next year. supposed to be a good canner too.
usually with pole beans, you get a small amount early, and then boom, you're picking every day or every other day for a few weeks. then they tail off some during the hot, hot days. keep them watered, and they will reward you with a smaller flush once the weather cools some. there will be some variance depending on variety. thats my experience growing in michigan

keith