Yes. Hiroshima and Nagasaki were on August 6th and 9th. There were plans for another bomb to be dropped in late August. Here we can see that one might have been ready for delivery as early as the 18th.

At the same time, we can see here that American intelligence was not sure how much of an effect atomic bombs would have after the first 2 stating explicitly:

"Large..undefeated Japanese ground forces have the capacity to offer stubborn resistance...Atomic bombs will not have a decisive effect in the next 30 days"

The thinking went that if the first two bombs did not convince the Japanese to surrender than it wasn't sure how many would (if at all). The power of the bomb was not only its destructive capacity but the effect it would have on the Japanese public and leadership ("shock and awe").

Despite these concerns, there were preparations to make bombs as far as October. Plans estimated developing at least 3 bombs a month. You can see that there was a debate on whether to drop bombs as they were made or whether to hold out as well.

What cities they may have targeted are unclear but the Target Committee had previously suggested five major cities. It's likely that one of them would've been next.