Urban thermal environment risk resulting from land use and land cover change (LUCC) has become the most significant barrier to urbanization processes and sustainable development of an urban ecological environment. However, there is currently limited information on risk identification, evaluation, and pre-controlling methods affecting the safety precaution and controlling measures of urban thermal environments. The present study established an Urban Thermal Environment Risk Model (UTERM) as follows:(1) normalized and classified the urban land surface temperature (LST) during three different periods; (2) established a spatio-temporal process prediction model for the urban thermal environment based on MARKOV-CA and further verified its simulation accuracy; and (3) set urban thermal environment risk rules and analyzed its spatio-temporal patterns. This study forecasted spatio-temporal patterns of the urban thermal environment of Beijing and further analyzed its characteristics during 2015-2020 through MODIS surface temperature products in summer and land use datasets at a 1:100000 scale between 2005 and 2015. The results showed that the urban thermal environment risk might be increasing in the Beijing metropolitan area. The proportion of an extreme-high risk area will reach up to 12.08% from 9.66% in 2020, which will mainly be distributed in Dongcheng, Xicheng, Chaoyang, Fengtai, Shijingshan, eastern Haidian, and northeast Daxing districts, and will expand along the east-west paths. There is a significant increasing trend for the number of patches and aggregation indexes of extreme-high risk patches, becoming more regular for their landscape shape. The method for quantitatively evaluating spatio-temporal patterns of urban thermal environment risk effectively provides theoretical and technical support for planning urban ecological spaces and preventing urban heat islands.