Sounds as if all the answers below (except for Murial; she "got it") missed the point. You're looking for something that'll be available in the future, not today. Her advice is good.
I'd also suggest having a Realtor go into the MLS and look for rentals that meet your criteria (location, price, number of beds and baths, etc.) that were on the rental market and closed in July in 2007, 2006, and 2005. These are properties that were rented, in which the leases probably are expiring or coming up for renewal in August. Many renters just stay 2 or 3 years...sometimes only 1 year. So some of those people will be moving out. Have your agent contact the owners and explain that he/she is working with a client who might be interested in renting the house; will it be available? In some cases, of course, the owners won't know; the renters won't have given notice yet. But in some cases the owners will know. And those owners will be absolutely delighted at the prospect of having another tenant without facing the prospect of a prolonged vacancy.
Hope that helps.