Tbilisi has a continental climate with hot summers and cold winters. The best times to visit are spring (April–June) and autumn (September–October), when temperatures are mild, the skies are generally clear, and the city is at its most comfortable. Spring brings lively street life and the year's first outdoor dining; autumn brings harvest festivals and the rtveli grape harvest in Kakheti wine country nearby.
July and August are hot — often over 35°C — and crowded with domestic tourism. The city stays lively but the heat can be oppressive in the middle of the day. Early mornings and evenings are pleasant; the old town lanes provide some shade. January and February are cold, with temperatures occasionally dropping below freezing and snow possible. The city doesn't shut down — Georgians are hardy — but the short days and grey skies reduce the appeal of outdoor sightseeing.
Tbilisoba, the annual city festival, takes place on the last Saturday of October and fills the old town with folk music, craft stalls, and wine. It is worth timing a visit around if you can.