In the early 1990s, a poet name Ka—fresh off of a 12-year exile in Frankfurt, Germany—returns to Turkey, the country of his birth and upbringing in order to write an article about a wave of suicides among young girls in the Eastern city of Kars. In reality, however, Ka is using this trip to Kars as an excuse to reconnect with Ipek, a beautiful woman from his past that he's heard recently separated from Muhtar, their mutual friend from college. On the way into the city, Ka is struck by the constantly falling snow, which reminds him not only of his innocent childhood, but also of isolation, brutality, and even divinity. Though Ka is a secular, humanist individual in the tradition of Europeans and Westernized Turks, he begins to wake up to a nascent sense of faith while in the city of Kars. He also is continually struck by the destitution and sadness of the city; for example, when Ka first arrives, he goes door to door to ask the families of the deceased girls about their deaths and is disturbed deeply. Though popular opinion says that many of these young suicides took their own lives because they were banned from wearing their headscarves at school by the secular government, Ka finds that their deaths owed more to systemic poverty and general unhappiness.
Early on in the city of Kars, Ka meets up with Ipek at a café, where they witness the assassination of the local director of the Institute of Education. From the scene of the assassination, Ka goes to speak with Muhtar, a candidate for mayor of Kars under the supervision of the Islamist Prosperity Party. After the police come and take both Ka and Muhtar in for questioning, Ka runs into a boy named Necip who takes him to meet with Blue, a prominent Islamist who is hiding in the city and who has been blamed for a series of religiously motivated crimes. Later that day, Ka pays a visit to Muhtar's Sheikh and reckons with his own rapidly developing religious awakening, as well as the new divine inspiration he feels to write poetry again. Afterwards, Ka runs into Necip again and finds him to be an honest and devout person with a passion for writing, as well as a deep love for a woman named Hicran, who leads the headscarf girls. Hicran, however, is really Ipek's sister Kadife, who shows up and escorts Ka back to her father's house for dinner. That night, a performance is planned featuring Sunay Zaim, a roaming actor with a sordid political and military past that Ka saw on his way into the city. Ka is also scheduled to perform a new poem at the performance, which is going to be broadcast all over the city.
Ipek convinces Ka to go to the theater and perform, which he does, but during Sunay's performance, a coup is staged against Islamists that leaves many dead or wounded. What's more, since the heavy snow has lead to road closures in and out of Kars, the coup's reign of terror is able to go on for many days. During the time of the coup, Ka is befriended by Sunay Zaim and also called on by Blue to issue an anti-coup statement to the West. It is in occupying this role of mediator between the junta and Islamists that Ka discovers some key facts—Kadife is Blue's mistress, Sunay is dying of heart disease, and Necip has been killed during the coup. Meanwhile, as Ka plays multiple roles in Kars politics during the coup, he is also falling more and more in love with Ipek and making preparations for the two of them to escape to Germany together. Eventually, their relationship is consummated during a secret meeting (organized by Ka) of various factions at the Hotel Asia, where a joint statement for the West is prepared by those opposed to the coup. Shortly afterwards, Blue is captured by Sunay's men.
A turning point comes in the novel when Sunay informs Ka that he is planning a second play just before the roads thaw and the city reopens. This play is to feature Kadife and will see her bare her head onstage, so Ka convinces Blue and Kadife both to participate in the proceedings in exchange for Blue's release. However, just before the second play, Ka betrays Blue because he finds out that he used to be in a relationship with Ipek. Once Blue dies however, Ipek refuses to return to Frankfurt with Ka and stays in Kars to watch her sister perform. During this play, Kadife kills Sunay with a gun that she thought was unloaded, and she becomes immortalized as an almost legendary figure. Four years later, in Frankfurt, Ka is killed on the street, and his poetry manuscript is stolen.
At this point, seeking to piece together the poetry written by Ka during his time in Kars (which heavily features the motif of snow and its symbolic relationship with human life), Ka's friend Orhan—who has been the narrator for the entire text—travels both around Germany and to Kars in order to retrace his friend's steps. There, he is entranced by Ipek's beauty and finds that Ka is hated by most of the people of Kars for his superciliousness and failure to take responsibility for his betrayal of Blue. One key person who speaks to Orhan is Fazil, an old friend of Necip's, who is married to Kadife and convinces Orhan to include some of his words in the final novel he is writing about Ka (i.e., Snow itself). These words are to never completely trust what an outsider says about Kars—the people there are not poor or caricatures to be pitied, but rather real people whose lives have every bit the same importance as a Westerner's or European's. After piecing together much of Ka's work and finding out that Ka did indeed betray Blue—an action which likely caused Ka's own death at the hands of Blue's disciples years later—Orhan then leaves Kars and watches it recede into the snow.
