October is a great month to visit Alsace. The vineyards are turning from green to yellow. Everything has most likely been harvested except for the grapes destined for Late Harvest and Noble Rot wines but it's still beautiful.
If you are lucky, they will be in the middle of harvesting...
My general rule is that you put on your coat for good after Halloween. Be prepared of course just in case, but most likely you'll only need a sweater or jacket. And sometimes the weather is even warm during the day if it's particularly sunny.
