In Hotwire's September 2012 Travel Savings Indicator report, which features the top five cities in North America where hotel, air and car rental rates have dropped the most as compared to the same time last year, Jackson, Miss. took the top stop in the month's biggest rate drop.

"Although the summer is coming to a close, the hotter-than-normal temperatures seem to be affecting certain destinations, curbing demand and causing prices to fall," said Clem Bason, president of the Hotwire Group. "While up north in Canada, there's some pricing competition among airlines resulting in good deals to a couple of their most popular destinations. Overall, this is a great time for travelers to take advantage of some incredible shoulder season deals to cities that typically don't discount." 

According to the Hotwire report, car rental rates on its site are "down all over the country." 

Hotwire's car rental prices are average prices based on bookings across all car and seat classes — actual prices may be higher or lower than the examples provided.

You can see here Hotwire's report for the month of August.