Why does it rain a lot in Houston?

Houston, Texas, is known for its humid subtropical climate, which means that it experiences hot summers and mild winters with abundant rainfall throughout the year. 

Houston experiences a significant amount of rainfall due to its location near the Gulf of Mexico, its geography in a low-lying coastal plain, and its warm and humid climate. 

In this article, we will discuss the reasons why Houston experiences so much rainfall and how it affects the city and its residents.

How much rain does Houston experience?

According to the National Oceanic and Atmospheric Administration (NOAA), Houston is the fourth rainiest city in the United States, behind Mobile, Pensacola, and New Orleans.

Houston receives an average of 49.77 inches (1264.1 mm) of rainfall per year, which is well above the US average of 38.61 inches (980.3 mm) per year. 

The city experiences most of its rainfall during the hurricane season, which lasts from June to November. 

In recent years, Houston has experienced several major flooding events, including Hurricane Harvey in 2017, which caused catastrophic flooding and resulted in 68 fatalities, according to the National Hurricane Center.

Location

The high frequency of heavy rainfall events in Houston can be attributed to the city’s location near the Gulf of Mexico, which provides a steady supply of warm, moist air that can fuel thunderstorms

The warm and humid air from the Gulf rises and cools, condensing into clouds and eventually leading to precipitation. 

During the summer months, the Gulf of Mexico provides a significant source of moisture to the atmosphere, which can add to the development of thunderstorms in Houston and the surrounding areas. 

In addition to thunderstorms, Houston is also prone to tropical storms and hurricanes, which can bring a lot of rainfall and cause flooding. 

Hurricanes are formed in the warm waters of the Gulf of Mexico and can move towards Houston, causing significant damage and loss of life. 

Houston’s location on the coast also makes it vulnerable to sea-level rise, storm surges, and coastal erosion, which can contribute to flooding and other weather-related impacts.

Topography

Another reason for the high rainfall in Houston is its geography. Houston is located in a low-lying coastal plain, which means that it’s vulnerable to the effects of tropical storms and hurricanes that form in the Gulf of Mexico. 

These storms can bring heavy rains and strong winds to the city, leading to significant amounts of rainfall in a short period of time. The flat terrain of the coastal plain also means that the rainwater has nowhere to go, leading to widespread flooding in the city.

Climate

According to the Houston National Weather Service, the city’s warm and humid climate also contributes to the high rainfall. The city’s average temperature is around 72°F or 22°C, with humidity levels often reaching above 70%. 

This warm and humid climate creates a favorable environment for clouds to form and for precipitation to occur. The city’s hot and humid climate also creates instability in the atmosphere, which can lead to thunderstorms and heavy rainfall.

During the summer months, Houston’s temperatures can climb into the upper 90s and lower 100s Fahrenheit, while humidity levels remain high. 

This combination of warm temperatures and high humidity provides an ideal environment for the formation of thunderstorms. As warm air rises, it cools and forms clouds, leading to thunderstorm development.

In addition to these large-scale weather events, Houston’s warm and humid climate can also produce smaller-scale weather phenomena, such as sea breezes and afternoon showers, which also bring rain to the city. 

Effects of Rainfall on Houston

The heavy rains and flooding in Houston can cause various problems for both residents and visitors alike. 

Some of the most common effects are problems with transportation and flooding. It may also have an impact on Houston’s economy, public health, infrastructure, and tourism. 

Flooding

The city’s drainage system, which was built for a maximum rainfall of 10 inches per year, is often overwhelmed by the amount of rainfall, leading to widespread flooding.

The frequent rainfall and associated flooding can cause damage to homes, businesses, and infrastructure. Due to the city’s flat terrain and low-lying coastal plain, heavy rain can easily accumulate in low-lying areas, leading to flooding.

In addition to its flat terrain, Houston’s geology also plays a role in its susceptibility to flooding. The city is built on a layer of soft, unconsolidated sediment, which makes it difficult for water to be absorbed into the ground. 

Instead, rainwater tends to accumulate on the surface, leading to flooding in low-lying areas.

Houston’s urbanization and development have only made the city’s flooding problems worse. The construction of roads, buildings, and other impervious surfaces has reduced the amount of land available for water to be absorbed into the ground.

As a result, when it rains, water tends to run off the surface and into drainage systems or waterways, leading to flooding.

Disruptions to Transportation and Mobility

Heavy rains in Houston can have a significant impact on transportation, both public and private. 

The city’s flat topography and low-lying coastal plain make it particularly vulnerable to flooding, which can cause significant disruptions to transportation systems.

Private transportation, such as cars and trucks, can be particularly affected by heavy rains in Houston. The city’s roads and highways can become flooded and impassable, leading to closures and delays.

Public transportation systems, such as buses and trains, can also be disrupted by heavy rain in Houston. Buses may be rerouted or canceled due to flooded roads, while trains may be delayed or canceled due to damage to infrastructure or safety concerns.

Flooding and severe weather conditions can also lead to cancellations and delays at the city’s airports, including George Bush Intercontinental Airport and William P. Hobby Airport.

Heavy rain can also impact other forms of transportation in Houston, including cycling and walking. Flooded sidewalks and bike paths can make it difficult for people to get around the city, particularly in areas that are prone to flooding.

Damage to Infrastructure

Heavy rainfall and flooding can cause soil erosion, leading to landslides and sinkholes that can damage infrastructure in Houston like roads, bridges, buildings, and other critical systems.

• Roads and Bridges
  • Floodwaters can damage roads and bridges, causing cracks and potholes that can make them unsafe for travel. In some cases, floodwaters can wash out entire sections of roads and bridges, rendering them unusable.

• Buildings and Other Structures
  • Significant damage to buildings can occur, especially those that weren’t designed to withstand these extreme weather events. Floodwaters can also cause mold growth.

• Utilities
  • Critical utilities, including water and sewage systems, electrical grids, and telecommunications infrastructure are also at risk. Damage to these systems can lead to power outages and water contamination.

• Environment and Wildlife
  • Heavy rain and flooding can also cause environmental damage, such as soil erosion, water pollution, and damage to wildlife habitats.

One instance of infrastructure damage in Houston from rains and floods occurred during Hurricane Harvey in 2017. 

According to the Greater Houston Partnership, the Buffalo Bayou, which runs through the city, experienced severe flooding that damaged infrastructure along its banks.

The flooding caused by Hurricane Harvey damaged the banks of the Buffalo Bayou, which in turn caused the erosion of the bayou’s levees and banks, and led to the collapse of some bridges and roads. 

The damage to these critical pieces of infrastructure disrupted transportation and communication in the city, making it difficult for emergency responders to reach those in need.

According to the news article, the damage caused by the flooding led to $125 billion in losses for the city. The extensive damage to infrastructure, including roads, bridges, and buildings, resulted in a prolonged recovery period for Houston and its residents.

Public Health Impacts

Heavy rains and flooding can have significant impacts on public health, safety, and wellbeing in Houston. 

• Water Borne Diseases
  • Floodwaters can become contaminated with sewage, bacteria, and other harmful substances, leading to an increased risk of waterborne diseases such as cholera, typhoid fever, and leptospirosis.

• Increase in Mosquitoes and Other Carriers
  • It can also create ideal breeding conditions for mosquitoes and other vectors that can transmit diseases such as dengue fever, malaria, and Zika virus.

• Chemical Waste
  • Accumulated water can also become contaminated with hazardous chemicals from industrial facilities, leading to potential exposure to toxins that can harm public health.

• Physical Injuries
  • Heavy rain and flooding can also lead to physical injuries, such as cuts, bruises, and broken bones, particularly for people who are forced to wade or swim through floodwaters.

• Mental Health
  • Floods can also have significant impacts on mental health, causing stress, anxiety, and depression, particularly for people who have lost their homes or are forced to evacuate.

• Access to Treatment
  • Rains and flood water can lead to road closures and disruptions to public transportation, making it difficult for people to access emergency services, healthcare, and other critical resources. 

One instance of severe flooding in Houston was during Hurricane Harvey. 

According to the CDC, The flood water was contaminated by sewage, biohazards, chemicals, and 8 million cubic yards of garbage. A huge area was affected by the flooding causing injuries, trauma, and sickness in the people living there. 

During that time, affected areas experienced a 200% increase in demand for medical attention. A fourth of the complaints were related to gastrointestinal issues and there was a significant increase in nausea-vomiting-diarrhea (NVD) visits. 

Economic Impacts

Additionally, the high rainfall in Houston can also have an impact on the city’s economy. 

• Tourism
  • The frequent rainfall and associated flooding can lead to a decrease in tourism, as visitors may be deterred by the rainy weather. 

• Disruption of Goods and Services Delivered
  • The heavy rains can also disrupt the transportation of goods and services, leading to decreased economic activity.

• Damage
  • Damage to homes, businesses, and other properties lead to significant repair and reconstruction costs. In some cases, flood damage can be so severe that buildings need to be completely demolished and rebuilt.
  • Flood water can also cause damage to critical infrastructure such as roads, bridges, and water treatment facilities, leading to repair and reconstruction costs.

• Transportation for Workers
  • The rain and flood can make it difficult for employees to access workplaces, leading to delays and lost revenue.

Programs in Place to Curb the Negative Effects of Rainfall

Houston has implemented several programs and initiatives aimed at mitigating the impacts of heavy rain and flooding. Some of these programs and initiatives include:

Floodplain Management

To mitigate the impacts of flooding, Houston has implemented several initiatives, including the Houston Galveston Area Council Regional Flood Management Plan. 

The plan is a comprehensive guide to flood management in the Houston area. Here are some important points from the plan.

1. Flood Risk Assessment: The plan includes a detailed assessment of flood risk in the Houston area, including the identification of flood-prone areas and the assessment of potential impacts of flooding.

2. Infrastructure Improvements: The plan includes recommendations for infrastructure improvements, such as the construction of new flood control structures and improvements to existing infrastructure.

3. Emergency Response Planning: The plan includes recommendations for emergency response planning, including the development of evacuation plans and the improvement of emergency communication systems.
4. Public Education: The plan emphasizes the importance of public education and outreach in flood management and includes recommendations for public education campaigns and community engagement initiatives.

5. Adaptation Strategies: The plan includes recommendations for adaptation strategies to address the impacts of climate change, such as sea level rise and increased frequency and intensity of extreme weather events.

Drainage Infrastructure Improvements

Houston has invested in significant improvements to its drainage infrastructure. These include the construction of detention basins and the expansion of drainage channels to help reduce flooding in areas prone to heavy rain.

The city has upgraded its drainage system, including the construction of new stormwater detention ponds, which help to reduce the risk of flooding by holding water during heavy rainfall events.

According to the Houston Government Council, some of the efforts by Houston to address this issue are as follows: 

• $572 million towards drainage-related capital improvement projects

> 42 completed and 13 currently under construction.

• $61 million for local drainage projects

> 218 completed and 75 active projects underway.

• $53.2 million in storm water action team (SWAT) projects

> 156 completed and an additional 22 due to be completed 

Emergency Response Plans

Houston has developed comprehensive disaster preparedness and recovery plans to ensure that the city is prepared to respond to flooding and heavy rain situations. 

The plan includes detailed guidance for emergency responders, as well as strategies for communication and coordination with other agencies and organizations. It focuses on the city’s efforts to recover from disasters and restore normal operations as quickly as possible. 

One of the key components of Houston’s Disaster Preparedness and Recovery plans is the Houston Emergency Operations Center (EOC), which serves as a central hub for emergency response and coordination. 

The plans include protocols for evacuations, sheltering, and other critical response activities. Some of the offered assistance services include the following: 

• 3-1-1 City of Houston helpline to report debris, hazardous material, or contaminants within the City of Houston 
• 346-286-4000: Harris County Flood Control District hotline to report a flooded home
• Towing services
• 866-659-0666: Lone Star Legal Aid’s Disaster Hotline for disaster legal assistance
• Recovery and Disaster Prep Websites 

Flood Warning Systems

Houston has implemented a flood warning system that provides residents with real-time information about flood conditions and potential hazards. 

The system includes automated alerts and notifications that can be sent to residents via text message, social media, and other channels.

One of the most comprehensive of these systems is the Harris County Flood Warning System. The system was established in the 1980s in response to a series of devastating floods that hit the Houston area in the 1970s.

The Harris County Flood Warning System is a network of rain gauges, river gauges, and other sensors that provide real-time information about water levels in rivers and streams throughout the county. 

One of the main goals of the Harris County Flood Warning System is to provide accurate and timely flood warnings to the public and emergency responders. 

The system includes more than 180 rain gauges and 150 river gauges, which are connected to a central computer system that processes the data and generates flood warnings when water levels rise above certain thresholds.

The flood warnings generated by the Harris County Flood Warning System are sent to emergency responders and the public through various channels, including social media, email, and text message. 

The system also includes a website where residents can access real-time information about water levels and track the progress of flooding in their area.

In addition to providing flood warnings, the Harris County Flood Warning System is also used to support emergency response efforts during floods. 

The system provides information about which areas are most at risk of flooding, allowing emergency responders to prioritize their efforts and allocate resources more effectively.

Buyout Programs

The Harvey Buyout Program is a program in Houston that was established in the aftermath of Hurricane Harvey, which caused widespread flooding in the city in 2017. 

The program aims to buy out homes in flood-prone areas and convert them into green space, parks, or other public uses. This is voluntary, and homeowners in flood-prone areas can choose to participate in the program if they wish.

To participate in the program, homeowners must first submit an application and meet certain eligibility criteria. This includes the location of the property, the extent of flood damage, and the homeowner’s income.

If a homeowner is approved for the program, they will receive a fair market value offer for their property. Homeowners can choose to accept or reject the offer, but if they accept, they must vacate the property and sign over the deed to the city.

Once the city takes ownership of the property, it will be converted into green space, parks, or other public uses. 

The goal of the program is to reduce the risk of future flooding in the Houston area, by removing homes from flood-prone areas and allowing natural flood plains to absorb excess water.