Joint Base San AntonioCommunity
Weather and Climate
The area’s main climate influences are tropical and desert; it lies near the western edge of the humid subtropical climate zone. The temperature has mild fluctuations from summer to winter, and humidity varies depending on the winds. The average annual temperature is 69 degrees. July and August are usually the warmest months of the year with an average maximum temperature of 95 degrees. Most precipitation falls in the late spring or early fall. During the winter, the area experiences a few subfreezing nights but snow is rare.
Every second counts in a disaster so planning and preparation can be lifesavers.
The city of San Antonio and Bexar County work with the Texas Division of Emergency Management and the U.S. Department of Homeland Security to strengthen local and national security. Go to www.readysouthtexas.gov to learn about potential threats and how to prepare for the unexpected. Explore www.saoemprepare.com to learn about the local hazards and what to do before, during and after an emergency.
The following are considered significant hazards in Texas.
San Antonio is a part of “Flash Flood Alley.” It is one of the most flash-flood prone regions in North America. A flash flood watch is issued when flash flooding is expected to occur within six hours after heavy rains have ended. A flash flood warning is issued for life- and property-threatening flooding that will occur within six hours. During a flash flood watch or warning, stay tuned to local radio or TV stations or a National Oceanographic and Atmospheric Administration Weather Radio station for further weather information.
If you are outdoors during a rainstorm, seek higher ground. Avoid walking through any floodwaters — even water 6 inches deep can sweep you off your feet. If you are driving, avoid flooded areas. The majority of deaths in flash floods occur when people try to drive through flooded areas. Roads concealed by water may not be intact, and water only a foot deep can displace a vehicle. If your vehicle stalls, leave it immediately and seek higher ground. Rapidly rising water can engulf a vehicle and sweep it away.
Some exposure to sunlight is good, even healthy, but too much can be dangerous. Broad-spectrum ultraviolet radiation, listed as a known carcinogen by the National Institute of Environmental Health Science, can cause blistering sunburns, as well as long-term problems like skin cancer, cataracts and immune system suppression. Overexposure also causes wrinkling and premature aging of the skin.
Cloud cover reduces UV levels, but not completely. Depending on the thickness of the cloud cover, you can still burn on a cold and overcast day, so be prepared with sunglasses, sunscreen, long-sleeved garments, wide-brimmed hats and an umbrella.
While more likely at certain times of year, thunderstorms can happen anytime. A severe thunderstorm can knock out power, bring high winds, lightning, flash floods and hail, and produce a twister in seconds. Pay attention to storm warnings. Remember the rule: “When thunder roars, head indoors.” Once inside, avoid electrical appliances, plumbing fixtures and use only a cordless telephone in an emergency. Unplug your desktop computer. Do the same with other plugged-in electronics or use surge protectors. The National Weather Service recommends following the 30/30 Rule: People should seek shelter if the “Flash-to-Bang” delay — length of time in seconds from the sight of the lightning flash to the arrival of its subsequent thunder — is 30 seconds or less and remain under cover for 30 minutes after the final thunderclap.
For more information, visit www.lightningsafety.noaa.gov.
Tornadoes can develop quickly, with minimal warning, so it is important to have a plan in place before they occur. If a tornado watch is issued, weather conditions favor the formation of tornadoes, such as during a severe thunderstorm. A tornado warning is issued when a tornado funnel is sighted or indicated by weather radar. You should take shelter immediately during a tornado warning.
Know where the safest place of shelter is in your home — a basement or an inside room on the lowest floor (like a closet or bathroom) if your home does not have a basement. Avoid windows and get under something sturdy, like a heavy table, and cover your body with a blanket or mattress to protect yourself from flying debris.
For more information, visit www.emergency.cdc.gov/disasters/tornadoes.