How are Hurricane Wind Speeds Determined?

When tropical storms and hurricanes are churning in the oceans, you may be hearing them called Cat 2 or Cat 3 storms. What does that mean and how do meteorologists determine the number? It’s actually pretty interesting, but not a job for the faint of heart.

Key Takeaways

• Hurricanes are categorized using the Saffir-Simpson scale based on wind speed
• A storm becomes a hurricane at 74 mph
• Meteorologists use satellites, aircraft, radar, and ocean data
• Flooding and storm surge often cause more damage than wind
• Even tropical storms can significantly impact business operations

How Storms Are Observed and Measured

While satellites, radars, and computer models help meteorologists understand the atmosphere, they are also critical tools for estimating storm strength, structure, and development in real time.

Hurricane categories are determined by maximum sustained wind speed over a one-minute period.

Meteorologists use advanced satellite techniques, such as the Dvorak method, along with microwave sensors and ocean-surface wind measurements to estimate wind speeds, even when aircraft are not present.

To gather the most precise data, especially when storms threaten land, aircraft reconnaissance may be used to directly measure barometric pressure and wind speeds within the storm.

Known as Hurricane Hunters, these crews fly specialized aircraft into tropical cyclones to collect critical data. Missions are conducted around the clock during active storms, typically every 3–6 hours.

Temperature, pressure, and wind data are recorded and transmitted back to the NOAA National Hurricane Center in real time. In stronger hurricanes, dropsondes are released into the eyewall to measure wind and into the eye to measure pressure.

Categories don’t tell the full picture. Even tropical storms can disrupt operations, supply chains, and business continuity.

When Does a Storm Become a Tropical Storm or Hurricane?

Before storms are categorized, they are first classified based on maximum sustained wind speed:

• Tropical Depression: ≤ 38 mph
• Tropical Storm: 39–73 mph (this is when a storm gets its name)
• Hurricane: ≥ 74 mph

These classifications are determined using a combination of satellite data, aircraft observations (when available), ocean buoys, and radar near land.

A Category 3 or above is considered a major hurricane.

Understanding the Saffir-Simpson Scale

Once data is analyzed at the National Hurricane Center, storms are categorized using the Saffir-Simpson Hurricane Scale.

Herbert Saffir was a civil engineer who was leading a study in 1968 about the damage different wind speeds would cause to homes. Robert Simpson, who was in charge of the NHC at the time, was having trouble communicating risk to the public. So, Simpson spoke with Saffir who in turn created a damage scale.

Initially, this scale also accounted for pressure and storm surge, but that was removed in 2009 and the SSHS became purely a wind scale. Storm surge and flooding are now forecast separately from the category rating.

The Saffir-Simpson Hurricane Scale estimates the potential wind damage a hurricane may cause to well-built homes and businesses based on its sustained wind speed.

How Hurricane Wind Speeds are Determined

Maximum sustained wind is defined as the highest average wind speed over a 1-minute period. This value is determined by combining multiple data sources, including:

• Aircraft measurements (and dropsondes)
• Satellite-based estimates
• Ocean buoys and surface observations
• Doppler radar (near land)

Aircraft are helpful but not required. Many storms are classified using satellite data alone.

Why Businesses Should Prepare, Regardless of Category

Whether your business is facing a Category 3 hurricane or a tropical storm, proactive planning is essential. Even lower-category systems can disrupt operations, damage infrastructure, and impact supply chains, especially when flooding and storm surge are involved.

Proactive planning, such as securing assets, preparing contingency plans, and monitoring trusted weather intelligence sources, can make a significant difference in minimizing risk.

Stay Ahead of Hurricane Season

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