The bees are busy gathering the last bits of nectar and pollen they can find. There are a few late blooming flowers that provide both of these (asters, rabbit brush etc) to help the hive prepare for the coming winter. They are also busy gathering propolis to seal the hive against drafts which can harm the colony while in cluster formation, drafts/cracks allow cold air to blow into the hive and can chill and kill the outer cluster bees and reduce the overall population which keeps the queen
and colony warm.
The workers are now starting to kick out almost all of the drones to help reserve the honey stores for those bees that will actually help the colony survive. A few drones may be retained throughout the winter for reasons not completely understood so if you see them flying on warm days don't be concerned (unless you see lots of them, then you could have a drone laying queen or an egg laying worker).
Although the work load is lessening, the work you do this month is critical. Check that your hives have enough honey stores to survive the winter; you need 60-100lbs of honey for your colony to survive. Check your hive by carefully lifting from the bottom back of the landing board; if the hive feels heavy and you can barely move it, you should be fine. If the hive moves easily and feels light, start emergency feeding so that the bees can store the food for winter use. Remember that winter feed is different from spring feed in that it is a 2:1 ratio (sugar/water). Feed until the first hard frost when the bees form a cluster or until they stop taking the feed, whichever comes first.
Take steps to prevent mice from getting into your hives, mouse guards or entrance reducers should do the trick. Add a windbreak to protect your hives if they are located in an area where winter winds are prevalent.
Ensure that the bees do have some ventilation at the top of the hive for the release of the moisture produced throughout the winter - if the moisture does not leave the hive, it will collect on the inside of the cover/inner cover where it will condense, chill and drip on the cluster causing sudden drops in temperature and will cause the bees to struggle. Another affect of poor ventilation is mildewing and molding on the frames which can sour the honey and give the bees nosema (dysentery) which can destroy a hive quickly.