A derecho (said with a softer “ch” as in “cheese” instead of a hard “ch” as in echo) is a line of intense, long-lived and widespread thunderstorms that move quickly across a long distance.

According to the National Weather Service, “if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length, then the event may be classified as a derecho.”

While the magnitude of damage from a derecho is often compared to the damage from a hurricane, derechos are not “inland hurricanes.” Hurricanes form around a central “eye” and have rotational winds that rotate around the center, while derechos form in a line and have straight-line winds that extend out from the derecho itself.

In North America, derechos are most common in almost every state sitting east of a line that extends from Montana to New Mexico and all the way to the east coast. During times of extreme heat, derechos may form as far north as the Canadian provinces of Saskatchewan and Manitoba. Around the world, derechos have also been recorded in Bangladesh and India, parts of Europe, and South America, South Africa and China.

While many people are unfamiliar with the word “derecho” because it is such a rare natural hazard, it was first used by Professor Gustavus Hinrichs in connection with a storm on July 31, 1877. There have been several significant derechos in the U.S., including seven multi-state derechos across the U.S. between the end of April and middle of July 2020. The Midwest derecho in August 2020 received more attention because of the extent of the damage and impact.

The year 2022 saw multiple severe derechos across North America, including at least three between December 2021 and July 2022 in the Central Midwest including Kansas, Nebraska, Iowa, South Dakota and Minnesota. On May 21, 2o22, a derecho swept through a section of Canada known as the Windsor-Quebec City Corridor, extending from the southern tip of Ontario through to Quebec City – a 721 mile (1161 km) section of the country that contains almost half of the country’s population. This derecho killed at least ten people and had winds up to 120 mph (190 km/h) – speeds that are equivalent to a Category 3 hurricane.

Key Facts

  • Derechos pose the highest risk to people engaging in outdoor activities. This is especially true for those who may not be close to shelter like when they are camping, hiking or participating in watersports. Derechos also pose a significant risk to outdoor workers such as farmers, those performing physical labor in areas far from shelter, and public safety or critical infrastructure workers who must work outside during dangerous weather conditions. The speed with which derechos can move means that people do not have the same amount of time to seek shelter that they would expect from a typical thunderstorm.
  • Derechos are so big that they may cover multiple National Weather Service (NWS) forecasting regions. The size and speed with which derechos move mean that some people may not get an advanced warning, especially if they do not have access to weather updates or wireless emergency alerts.
  • Undocumented people and temporary foreign workers are disproportionately at risk. Many people who are undocumented or are temporarily working in a different country will not have access to the same warning systems as permanent residents and natural citizens. Because of the lack of rural broadband wireless accessibility and the fact that many of them work in farming and other outdoor jobs out of cellular phone coverage, they are less likely to receive an emergency notification and less likely to have suitable shelter in the event of a derecho.
  • Marginalized communities are often affected more significantly than others after a derecho. In a webinar from the University of Iowa entitled Derecho, Disaster & Disadvantage: How natural disasters impact marginalized communities, Dr. Eric Tate said that disasters amplify the pre-disaster trajectory – if a group was struggling before a disaster, then after a disaster their situation is worse. In the same webinar, Dr. Tate suggests that looking at disaster relief programs through the lens of equity instead of economics would enable these programs to better serve those who need help the most instead of those who are most easily able to access them.
  • As heat waves increase in duration and frequency, derechos will follow. Derechos are most common during heat waves as they will form along the boundary of the heatwave and race along the border between the hot, high-pressure system and the cooler systems around it. As climate change brings more extreme temperatures for longer periods of time, the conditions allowing derechos to form will become more common – increasing the number of derechos.

How to Help

  • Support improving the accuracy of prediction and warning systems. Though many improvements have been made, derechos remain difficult to predict. While forecasters can identify the conditions that make a derecho more likely, the designation of a weather system as a derecho happens during or after the system passes through. Improved warning systems, such as those that call a home or wireless phone, are more reliable than warning sirens. However, these systems can cost hundreds of thousands or millions of dollars to introduce to a heavily-populated area and ongoing maintenance of these systems can require one or more full-time employees. FEMA introduced the Wireless Emergency Alert system, which sends text messages via wireless phones in the event of an emergency, and the National Weather Service can also send severe weather alerts during a derecho, but neither of these systems can reach everyone across a widespread rural area.
  • Help fund informational programs for those living in the most at-risk areas. Overcoming misinformation related to derechos is important. Derechos are not “inland hurricanes” or very large tornadoes; they are a distinct weather phenomenon and should be treated as such. Yet, many people are unaware of their risk because derechos are such rare events.
  • Fund building code changes and support structural improvement. In the areas most vulnerable to derechos, a typical home can withstand winds of 80 miles per hour, roughly equivalent to an EF0 tornado. Building houses, offices and other structures to withstand tornadoes will also improve their resilience toward derechos because there is significant overlap in the areas where tornadoes and derechos are most common. Improved building methods could help reduce future death and destruction. Some simple steps, such as anchoring manufactured homes to concrete foundations or reinforcing garage doors, could make a significant difference. Advocacy and awareness raising of the importance of these types of enhancement to become mandatory parts of the building code instead of additional options are key to changing how homes are built in areas commonly impacted by derechos.
  • In the aftermath of a devastating derecho, immediate needs are sometimes met by an outpouring of response, but full recovery can take years. These rare weather events can level government buildings, businesses, crops, farms and homes. When schools are damaged, particularly in small communities, life cannot return to normal. When businesses are damaged, the community’s economy suffers. Long-term recovery efforts must focus on creating a plan to minimize future damage, such as strengthening buildings and building codes, helping disadvantaged populations to receive legal aid to navigate FEMA rules, and providing low-interest loans to small businesses. After the 2020 derecho, the Marshalltown (Iowa) High School class of 1969 raised enough money through fundraising efforts to replace all the trees lost in the derecho, the 2018 tornado that also devastated the community, as well as plant additional new trees. These trees must be planted over a 10-year period to ensure the right mix of species and growth stages so that they have the best opportunity to survive and thrive.

What Funders Are Doing

Because derechos are rare, there has not been a significant amount of support directed towards derechos specifically. However, with derechos gaining prominence as more than just “bad thunderstorms,” more funds are being directed towards them.

The Center for Disaster Philanthropy (CDP) awarded $85,000 through its Midwest Early Recovery Fund to Matthew 25 in 2022. The grant will support home repair for low-income and under/uninsured households in Linn County, Iowa in response to the August 2020 derecho. The homes to be repaired are primarily manufactured homes and a resource guide about repairing manufactured homes after a disaster will be developed.

In response to the August 2020 derecho event, many philanthropic and corporate organizations stepped up to provide support in unique ways:

Learn More

We welcome the republication of our content. Please credit the Center for Disaster Philanthropy.

(Photo: Derecho damage in Iowa, 2020. Source: USDA)