A single hurricane can grow wider than the entire state of Texas or the country of France.

The size of a tropical cyclone is typically measured by the radius of its outermost closed isobar or the extent of its gale-force winds. In 1979, Typhoon Tip set the record for the largest tropical cyclone ever recorded in the Pacific Ocean. It reached a diameter of approximately 1,380 miles, which is nearly half the size of the contiguous United States.In contrast, the Atlantic's largest storm on record was Hurricane Sandy in 2012. Sandy reached a diameter of about 1,100 miles as it approached the Northeastern United States. These massive dimensions are driven by complex thermodynamic exchanges between the warm ocean surface and the atmosphere, fueled by water temperatures of at least 80 degrees Fahrenheit.The forward speed of a hurricane is controlled by large-scale atmospheric steering currents like the Bermuda High. When these steering currents are weak, a storm can stall or move at speeds under 15 mph. This phenomenon was seen during Hurricane Harvey in 2017, where the storm's slow movement led to over 60 inches of rain in parts of Texas.Meteorologists at the National Hurricane Center use satellite imagery and dropsondes to monitor these vast wind fields. Understanding the size is critical because a larger storm surge can be generated by wider wind fields, even if the peak wind speeds are lower. This makes the total diameter of the storm just as dangerous as its category rating.