Sessions still continue in 10 states, but not all of these are the states you'd expect to see active in October.
California is still in two special sessions on transportation and health care financing that were called for by the governor in June, and Illinois is locked in a budget standoff that has slightly spoiled their May 31st end-of-session date. Florida and Alaska also recently came back for special sessions on state senate redistricting and a natural gas pipeline project, respectively. You can easily view which states are still in session using MultiState's interactive session map.
Wondering when the 2016 session starts in your state? MultiState has released their 2016 Projected Session Dates & Prefiling Chart so you can hit the ground running. Alabama, Florida, Kansas, Kentucky, Mississippi, New Hampshire, Tennessee, and Utah have already begun their prefiling periods, and eight more states will join them in November. You can keep track of legislation as it comes in using ISRI's State Legislative Tracking System, available on the State Policy page; just contact Justin Short if you'd like some pointers on how to use the system for you or your staff!