The Chattahoochee River divides Georgia into separate climatic regions. The mountain region to the northwest is colder than the rest of Georgia, averaging 39°F (4°C) in January and 78°F (26°C) in July. The state experiences mild winters, ranging from a January average of 44°F (7°C) in the piedmont to 54°F (12°C) on the coast. Summers are hot in the piedmont and on the coast, with July temperatures averaging 80°F (27°C) or above. The record high is 113°F (45°C) at Greenville on 27 May 1978; the record low is –17°F (–27°C), registered in Floyd County on 27 January 1940.
Humidity is high, ranging from 82% in the morning to 56% in the afternoon in Atlanta. Rainfall varies considerably from year to year, but averages 50 in (127 cm) annually in the lowlands, increasing to 75 in (191 cm) in the mountains; snow falls occasionally in the interior. Tornadoes are an annual threat in mountain areas, and Georgia beaches are exposed to hurricane tides.
The growing season is approximately 185 days in the mountains and a generous 300 days in southern Georgia.