There's quite a wide range of climates in Georgia, from the warm, humid, subtropical Black Sea coast, via the colder, wet, alpine climate of the High Caucasus, to the arid steppes of the east.
The best times to visit Georgia are in May, June and September, when it is warm and sunny but not overly hot. July and particularly August are uncomfortably humid in many parts, and temperatures regularly reach 40°C. However, this is an excellent time to be in the mountains, where it is sunny and cool. This is also the peak season on the Black Sea. Winter can be grim everywhere, although thanks to the buffer of the Caucasus Mountains which protects the country from the icy northern winds, Georgia rarely freezes. There is a surprising amount of rain year-round.
Temperatures in the mountains range from an average -4.6°C in February to 16.4°C in July and August, with an annual average of 5.7°C. In Svaneti the winter lasts for up to eight months, with an average temperature of -15°C; it gets even colder on the high bare plateaux of Javakheti where temperatures drop to -30°C. On the coast of Adjara, temperatures range from 5.8°C in January to 23.8°C in August, with an annual average of 14.5°C; on the Abkhaz coast temperatures are slightly lower in winter, noticeably warmer in April and May, but virtually the same in high summer. In eastern Georgia temperatures range from 0.5°C in January to 23°C in August, with an annual average of 11.8°C, and in the south they range from -2.1С in January to 20.1С in August, with an average of 9.1С.
The weather in the Caucasus is more stable than in the Alps. In June there may still be too much snow for high hikes; July and August have the best weather, but even then it can drop to -10°C at 3,000-3,500m. Lower altitudes can often be hot and humid at this time of year, and the inhabitants of Tbilisi and Kutaisi flee to the coast or the mountains.
Precipitation ranges from 2,800mm in Abkhazia and Adjara to 300-600mm in the east (with 462mm in Tbilisi), and about 1,800mm at the main Caucasian passes. There's an average of 1,350-2,520 hours of sunshine per year (four-seven hours per day) in Tbilisi.