The Data Behind Wind Factor™️

Wind Factor uses the First Street Wind Model to find wind risks across the United States.

  • 68.1M
    Properties with risk
  • 76.7M
    Properties with risk in 30 years
  • 12.7%
    Increase in properties with risk
Wind Map 2min

Wind Factor distribution of properties at risk* (143.8M analyzed)

  1. Minor - 43.2M
  2. Moderate - 16.1M
  3. Major - 22.6M
  4. Severe - 10.4M
  5. Extreme - 15.0M

* Risk is calculated as experiencing at least tropical storm winds (39 mph) over 30 years.

Providing first-of-its-kind wind analysis

The First Street Wind Model is focused on how climate change is impacting wind risk to structures within the US. Changes to hurricanes’ intensities and their distribution are forecast to be the largest impacts of climate change on wind risk. The model builds off of decades of scientific peer-reviewed research and forecasts how hurricanes and costs from resulting wind damages to structures will change over time due to changes in the environment.

Analyzing major winds

The First Street Wind Model considers a location’s current and future risk specifically from hurricane winds. To build an understanding of this risk, tens of thousands of synthetic, computer-modeled hurricane tracks are used to build estimates of likely wind speed under the influence of a changing climate. For every location, the likely exposure to extreme wind is calculated for today and 30 years into the future and takes into account the local conditions such as the roughness of the landscape surrounding a property.

Note that while there is some recent evidence surrounding climate change’s impacts on the locations of tornadoes, convective storm wind events (such as thunderstorms), winter storms and nor’easters, at this time those storm types’ climate-related damages are still an active areas of research and are not yet included in the model. That said, tornado and thunderstorm risks are noted in the Wind Factor reports and historic information on these risks are included where available.

Calculating and mapping wind risks

The First Street Foundation Wind Model is a geospatially-varying wind model, which means it considers how a location’s likely exposure to high-speed winds is affected by climate change’s impacts. These impacts are related to forecast changes in hurricane intensities and their tracks, as well as the property’s characteristics, and use that information to assess the likely damages that would result from a property’s exposure to extreme wind.

    Storm tracks
    Charleston, South Carolina
    Probability of wind speed, 10KM x 10KM

The model builds a probabilistic forecast of the likely wind speeds for each location in the US by using multiple datasets from the National Oceanic and Atmospheric Association (NOAA), climate models from the WCRP CMIP6, and simulated hurricanes provided by Dr. Kerry Emanuel of MIT and sampled by Rhodium. Local variations in wind speeds are driven by the land surface roughness of the surrounding area that impacts how winds may be slowed as they flow across the earth’s surface.Note that other related climate risks from hurricanes, including from storm surge and heavy rain, are considered in the Flood Factor® model, also available from First Street Foundation.

Determining future wind exposure

The inclusion of environmental changes that impact future wind risk is an essential part of the First Street Foundation Wind Model. The model uses the WCRP CMIP6 SSP245 scenario to forecast how environmental conditions will change 30 years into the future, how those conditions will influence hurricane intensities and tracks, and uses those future hurricane characteristics to create a property-specific wind speed probability model. This allows the First Street Foundation Wind Model to predict likely wind speeds and associated damages 30 years from now and builds upon previously-published science to create new applications that pass the same rigorous standard of scientific peer review.

Simplifying wind risks

With weather forecasts, wind speeds are not often thought of on a property-by-property basis, but are instead usually thought of as impacting a wide area. For any analysis of extreme wind to be useful to a property owner, it has to be more specific and answer the question “How will high winds impact the buildings on this property?”. This includes estimates of the surface roughness of the topography surrounding a building, which can vary from smooth (adjacent to a large body of water) to rough (near mountains and hills).

Scoring system for properties

Once the wind speeds under a range of likely occurrence intervals or “return periods” have been calculated at a property level for both this year and 30 years into the future, the aggregate value of wind speeds over that time period is taken in order to arrive at a single score that represents how likely a specific location is to experience extreme winds. A property’s Wind Factor is based on that 30-year estimate, which means that a property with a higher Wind Factor currently has a higher likelihood to experience higher winds more frequently today and in the future than a property with a lower Wind Factor score.

Measuring the effect of wind on damages

Given the likelihood of wind events and estimates of their severity, the probable damages that will be incurred by a structure may be estimated by engineering professionals. In conjunction with Arup, a global engineering firm that specializes in structural engineering and damage estimates, First Street has developed an estimate of the average annual loss (AAL) for every building impacted by extreme winds – the AAL is the average cost of damage a home could expect, in average over many years on a per-year basis. While hurricane strength is usually categorized by the sustained 1-minute duration wind speeds within the storm, the most extreme damages to the structure are usually caused by the 3-second duration gusts that are a result of small-scale vortices and fluctuations in wind speeds. These gusts impart the greatest stress on the building, and their magnitude is estimated statistically from the sustained wind speed, and the magnitude of those gusts is used to estimate the AAL.

Sample of contributing factors to higher home vulnerability estimates

The angle of incidence of the winds upon the structure also can mean greater drag and stress on the roofs, walls, and windows of a structure. The angle between the most likely wind direction and the longest face of each structure is also used to determine the AAL. The First Street Foundation’s Wind Model combines open-source data on building characteristics, footprint location, square footage, and construction year to include a calculation of the AAL for each home over a 30-year period.

Ensuring scientific accuracy

The First Street Foundation Wind Model brought together top climate scientists, modelers, engineers, technologists, and analysts. Results of the model have been computed for the US, and compared against historical hurricane wind damage data, and historical hurricane tracks. Using Open Science protocols, all methods used by the First Street Foundation Wind Model have been submitted to scientific peer-review journals and are open to review on the Risk Factor website.

Continuously improving over time

First Street Foundation has made its wind model’s full technical methodology available to the public because it supports Open Science with scientific collaboration and data transparency to help instill trust in the model results. The First Street Foundation Wind Model will continue to incorporate feedback and improve its model over time, including annual data updates as new data become available.

Why are wind risks increasing?

A changing environment means higher temperatures and changing humidity, creating conditions which facilitate hurricane formation and intensification.

What can be done to address wind risk?

Although wind risk can never be completely eliminated, there are a number of steps homeowners can take to understand and reduce that risk.

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