In chapter 11, the Giver shares a memory of sledding in the snow with Jonas, who has no concept of snow because he has grown up in a highly structured, completely safe community that is established on the concept of Sameness. When Jonas asks the Giver why there is no longer snow in the community, the Giver tells him that Climate Control has prevented snow from falling and making it difficult to produce agricultural products. Jonas's community has been reconstructed to reflect the concept of Sameness, which makes the environment completely predictable and safe while simultaneously altering the majority of the citizens' ability to see in color or hear music. Growing up in a community established on Sameness, Jonas has never had the opportunity to experience a snowfall or ride down a hill. Unpredictable weather and difficult landscapes do not exist in Jonas's community and he can only experience them by receiving memories of the past from the Giver. Sameness results in a structured, organized community, which is comfortable, unpredictable, and safe.
It is in Chapter Eleven when Jonas receives the memory of somebody sledging down a hill in snow. He is completely perplexed by snow, as he has never seen it before and is transfixed by the white powder that is all around him and which continues to fall. After the memory has finished, he asks the Giver why it is that they do not have snow in their own world, curious as to why his present is so different from the past of humans that he is now able to experience through the memories he is being shown. Note the explanation that the Giver supplies him:
Climate Control. Snow made growing food difficult, limited the agricultural periods. And unpredictable weather made transportation almost impossible at times. It wasn't a practical thing, so it became obsolete when we went to Sameness.
In this technologically superior world, the weather is something that can be completely controlled and manipulated according to the wishes of man. This is why Jonas has never seen snow before in his life: it has not snowed in this future world for a very long time now. The way in which the weather is controlled so strictly is of course a symbol of the strict control that characterises this society, and also its lack of freedom.