Houston, Texas, is highly vulnerable to the impacts of tropical cyclones due to its location on the Gulf Coast. While a direct hurricane landfall on the city center is uncommon, the effects of storms moving ashore nearby are a recurring threat. The region must constantly prepare for the hurricane season, which officially runs from June 1st through November 30th.
The Geographical Reality
Houston is situated on the Gulf Coastal Plain, approximately 50 miles northwest of the Gulf of Mexico near Galveston. This inland distance provides some protection from the most catastrophic storm surge that batters the immediate coastline. The city’s topography is notably flat, rising only about one foot for every mile away from Galveston Bay.
This flat terrain, combined with the region’s expansive network of bayous and underlying clay soil, dictates Houston’s risk profile. The clay soil is poor at absorbing large amounts of water, leading to rapid surface runoff. Four major bayous—Buffalo, Brays, White Oak, and Sims—act as the primary drainage system, but they are often overwhelmed during severe rain events. This geography makes the area highly susceptible to flooding, even from storms that are not major hurricanes.
Historical Case Studies
Houston’s history is marked by several modern storms that illustrate the diverse threats tropical cyclones pose. Hurricane Ike in 2008 made landfall as a strong Category 2 storm near Galveston. Its massive wind field brought hurricane-force gusts and significant storm surge into Harris County. Downtown Houston experienced wind damage, including blown-out skyscraper windows, and power outages affected millions for weeks.
Tropical Storm Allison in 2001 demonstrated that a storm does not need high winds to cause widespread devastation. This slow-moving storm delivered up to 38.6 inches of rain over six days, causing more than $5 billion in damages and flooding tens of thousands of homes. The extensive rainfall overwhelmed the bayous and inundated the downtown tunnel system and the Texas Medical Center.
Hurricane Harvey in 2017 provided the most extreme example of a rainfall-based disaster. The storm stalled over the region, dropping over 40 inches of rain in a four-day period, with some areas receiving over 50 inches. Harvey’s catastrophic rainfall inundated hundreds of thousands of homes, displaced more than 30,000 people, and prompted over 17,000 rescues. This event is tied as one of the costliest tropical cyclones on record in the United States, with an estimated $125 billion in damage.
Understanding the Primary Threat
The most significant and recurring threat to Houston from tropical systems is inland flooding caused by excessive rainfall. The city’s immense urban sprawl has covered vast areas with impervious surfaces like concrete, asphalt, and rooftops. This rapid urbanization prevents rainwater from soaking into the ground, increasing runoff and sending large volumes of water quickly into the drainage system.
The flat terrain exacerbates this issue, as water moves slowly and has nowhere to go once the bayous are full. The city relies on two large flood control projects, the Addicks and Barker reservoirs, located in western Harris County. These reservoirs temporarily store water to reduce downstream flooding along Buffalo Bayou. During extreme rain events like Harvey, they fill to capacity, requiring controlled releases that can cause flooding in developed areas both upstream and downstream.
The lesser threat of direct, high-category wind damage or catastrophic storm surge is generally confined to immediate coastal areas like Galveston and the Bolivar Peninsula. However, the sheer size of a storm, as seen with Ike, can extend damaging winds and surge far inland. For Houston, the combination of its geography, urban development, and the tendency of storms to stall makes rainfall and subsequent flooding the dominant hazard.
Preparedness and Safety Measures
Houston residents should be proactive by creating a comprehensive household plan, including a designated meeting place in case of separation. Preparation must also involve assembling an emergency supply kit stocked with water, non-perishable food, flashlights, and a battery-powered radio for at least three to seven days. Keep copies of essential documents, such as insurance policies, in a waterproof container.
Understanding official alerts is a primary safety measure. A Hurricane Watch means impacts are possible, while a Hurricane Warning means impacts are expected within 36 hours or are currently happening. Residents should know their designated Evacuation Zone and only evacuate when ordered by local authorities to prevent unnecessary traffic congestion. Registering with programs like the State of Texas Emergency Assistance Registry (STEAR) is recommended for individuals with disabilities or special needs.