Seasons

Westeros's climate shifts from arid and dry desert climate in the furthest south to cold and harsh winters in the north and icy wasteland in the Lands of Always Winter in the farthest north.

Westeros and Essos both experience extremely long seasons of varying length, usually lasting at least a couple of years each. The maesters try to predict the length of the seasons, monitoring the temperature and days length, to advise on when to plant and when to harvest and how much food to store. However, given the random nature of the seasons, this is not something that can be relied on.

Days are longest in summer, shorter in other seasons, and shorter in the far north. Food can be grown in a glass garden in winter.

The Red Spring
As the harsh five-year winter began to recede the realm celebrated. The Fourth Blackfyre Rebellion began in 238. The war saw the realm torn asunder, not one House was spared from the harsh war that is regarded as one of the bloodiest since the Conquest. The Red Spring was named for both the blood spilled by all in the war, and the victors of the war; the Red Dragon.

The Blessings
The Blessings refers to the 23 consecutive years of Spring & Summer, leading to harvests greater than any had ever seen. Prior to the start of the Blessings, in the final moon of the Winter, the realm felt the earth beneath their feet shake. Some buildings in King's Landing lost some bricks and roofings, Storm's End reportedly swayed back and forth, and Planky Town reported that some of their docks were damaged. The eastern coast of Westeros from Gulltown to Planky Town experienced a small one meter wave that was not stopped by land. Minimal damage resulted from it, other than some docks and sunk ships.

The Sunny Spring
Named simply, the Sunny Spring is the longest Spring in living memory. It marks the start of the Blessings.

The Great Summer
The longest Summer in living memory, and the latter half of the Blessings. Some of the more southern kingdoms recorded heat greater than they had ever felt before during the peak of the Great Summer.

The Black Autumn
This autumn marked the ending of the Blessings, and the beginning of many years of sorrow. It was also the longest Autumn in living history. In 288, the Name Day Plot (the Sixth Blackfyre Rebellion) occurred which saw the death of the heir Prince Maekar. In 293, Prince Baelor drowned during a horrid Autumn storm in the Blackwater. Some also attribute then-Prince Viserys' conversion to the Red God to the naming of this season.

The False Spring
The Spring fooled every man, woman, and child in the realm. A harsh three-year winter had let up, and temperatures began to rise. The Citadel sent out their white ravens, only to send out another six moons later announcing the return to Winter when temperatures plummeted and snow was observed as far south as Highgarden.