Houston division. However, Houston is most accurately classified as being within Southeast Texas, a subregion of East Texas. Rivers Lakes and reservoirs Choke Canyon Reservoir Lake Corpus Christi Falcon Lake Lake Amistad Lake Findley Mitchell Lake Lake Casa Blanca Brauning Lake Calaveras Lake Bays Corpus Christi Bay San Antonio Bay Baffin Bay Nueces Bay Oso Bay Copano Bay Aransas Bay Matagorda Bay Lavaca Bay Redfish Bay Mission Bay Estuaries and waterways Rincon Bayou - a bayou in the Nueces River Delta, just north of the mouth of the Nueces River, for Location, see Nueces Bay Elm Bayou - a bayou on the Victoria-Refugio County line Gulf Intracoastal Waterway - a navigable route along the Gulf of Mexico without many of the hazards of travel on the open sea Resacas of the Rio Grande Valley - many oxbow lakes found scattered throughout the lower Rio Grande Valley Laguna Madre - a long, hypersaline bay that creates a barrier between Padre Island and mainland Texas Islands Padre Island North Padre Island South Padre Island Mustang Island Matagorda Island Ward Island San José Island Climate The climate of South Texas is varied. The area along the Mexican border is generally semi-arid (Köppen climate classification BSh), while the area from the coast inland to just west of San Antonio has a humid subtropical climate (Köppen Cfa). South Texas weather is affected by the Sierra Madre Oriental mountains to the west, the Gulf of Mexico to the east, and the Chihuahuan Desert to the west/northwest. Moisture from the Pacific is cut off by the Mexican Sierra Madre Occidental and Oriental mountain ranges. Along the coast the climate is best exemplified in the summers when humidity is extremely high though at times arid, depending upon whether tropical moisture from the Gulf and sometimes from the Pacific is flowing in or if the region is cut off from any moisture by high pressure systems, causing long droughts, which occur every few years. Temperatures reach freezing only a few times in the winter and snowfall is rare, usually three inches or less. Summers in this zone are hot and humid, with daily averages above . In addition, areas in Texas that are slightly inland from the Gulf of Mexico, such as San Antonio that border the semi-arid climate zone, generally see a peak of precipitation in the spring, and a deep, drought-like nadir in midsummer. The region itself