It’s cooling down in the lowlands and still warm enough to enjoy the mountains into October. Georgia has a LOT of trees, so the autumn colors are a delight. In a country where wine is a national passion, the grape harvest (late September to late October) is the focus of much feasting, music and merrymaking, especially in the main wine-making region, Kakheti (east of Tbilisi).

Source: https://www.lonelyplanet.com/georgia