Unintentional nonfire-related (UNFR) carbon monoxide (CO) poisoning is among the leading causes of unintentional poisoning deaths in the U.S. Our objective was to determine risk factors for UNFR CO poisoning deaths during the cold season in New York City (NYC). We examined data from death certificates and NYC Office of Medical Examiner records to describe decedent demographics, exposure circumstances, and CO sources during the cold months (October–April) between 2005–2013. Over the study period there were 32 UNFR CO deaths, with an average annual death rate of 0.4 per million people. Average annual cold-season death rates were higher among older adults (1.2 per million people ≥65 years) and men (0.8 per million men). The most common source of exposure was automobile engines (n = 15, 47%). The UNFR CO poisoning death rate in NYC is lower than the national average. Older adults and men are at greatest risk of death. Automobile exhaust is a significant and preventable source of exposure and should be emphasized in public health messaging and prevention efforts.