The concept of climate carrying capacity has been proposed recently for climate risk management. Based on identification of the concept of climate carrying capacity and analysis of the relationship among its influencing factors, this study established a comprehensive assessment indicator system of climate carrying capacity from aspects of the climate situation, the level of climate usage, and the development potential of cities. Taking Shanghai City as a case study, we developed a quantitative assessment model of climate carrying capacity. The climate carrying capacity and its influencing factors were analyzed and discussed in relation to the period 2004–2013. The results were as follows. (1) Current climate natural capacity indicator showed that the climatic situation of Shanghai City was inferior to its base climatic value and it had been in a state of fluctuation. (2) The climate stress and urban coordinated development capacity indicators increased steadily, but the growth rate of the urban coordinated development indicator was less than the growth rate of urban climate stress. (3) The climate carrying capacity was far lower than the benchmark value and it had been in a state of fluctuation mainly due to the effect of current climate situation. (4) According to a principal component analysis, seven factors of urban population density, per capita GDP, energy consumption per unit GDP, total industrial output value, investment in environment protection, spending on science and technology, and green area per capita were main influential factor of climate carrying capacity. It was proved that the proposed system for assessment of climate carrying capacity of a city was feasible. It can be used to describe the spatiotemporal changes of cities, and identify problems of regional climate carrying capacity associated with their development and function. This assessment system can provide a reference for the construction of an early warning system of climate carrying capacity for cities.