Climatologically, Texas has three major climatic types: Continental, Mountain, and Modified Marine climate, which is a subtropical climate and caused by the onshore flow of tropical maritime air from the Gulf of Mexico and modified by intermittent seasonal intrusions of continental air. Austin and San Antonio area, which is called South Central Texas division by National Weather Service, lies in the Modified Marine climate, the subtropical subhumid zone. Its annual precipitation in this area is around 1000 mm, and it is known for frequent flooding events, particularly in the recent 30 years. This study first analyzes the variation of the ground observations of temperature, precipitation and extreme weather events in the past up to 150 years, then compares these local climate variations with regional and global climate variation/change and cycles, next examines the relationship between local climate variation and cycle and extreme weather events, and finally assesses the impact of local and global climate variation/ change on the local extreme weather events. The further study will explore the influence of land use and land cover change on rainfall runoff and forecast the flash flooding caused by storm rainfall.