Hail is precipitation composed of solid ice lumps that develop within the powerful updrafts of a thunderstorm. The danger of a hailstorm relates directly to a hailstone’s size and velocity, which creates immense kinetic energy upon impact. This phenomenon poses a significant threat, capable of causing millions in property damage, devastating agricultural harvests, and presenting an immediate risk of severe injury to people and livestock.
Classifying Hail Size and Impact Severity
The severity of a hailstorm is quantified by the size of the hailstones, which meteorologists compare to common objects for reference. Hailstones smaller than one inch in diameter, such as pea-sized or nickel-sized ice, typically cause minor damage but can still harm delicate plants. The official threshold for a storm to be classified as “severe” is hail measuring one inch in diameter, roughly the size of a quarter.
Hailstones the size of a golf ball or a baseball fall with substantially greater terminal velocity. The speed of a one-inch hailstone ranges from 25 to 40 miles per hour, but very large hailstones exceeding four inches can reach speeds over 72 miles per hour, potentially surpassing 100 miles per hour. The kinetic energy increases dramatically with both mass and speed, turning the ice into a highly destructive projectile. For instance, a softball-sized hailstone (four inches) is rare but carries enough momentum to cause catastrophic damage to structures and vehicles.
Immediate Risks to Human Safety
The direct threat to human health from hailstones primarily involves blunt-force trauma from the high-velocity impact of large ice chunks. Common injuries reported during severe hailstorms include lacerations, deep bruises, and concussions. The head and exposed skin are the most frequently injured areas. While the majority of injuries result from direct impact, a significant portion also results from secondary mechanisms, such as slips and falls while people attempt to escape the storm.
While severe personal injury from hail is statistically less frequent than property damage, fatalities are possible with extremely large hail. A person caught outside during a storm producing grapefruit-sized hail can sustain life-threatening head injuries, including skull fractures. Even smaller hail driven by high winds can cause injury, underscoring the necessity of seeking immediate and sturdy shelter when a severe weather warning is issued.
Widespread Damage to Property and Agriculture
Hail is consistently one of the most costly weather hazards, accounting for billions of dollars in damage annually to personal property and the agricultural sector. Vehicles are particularly susceptible, often sustaining widespread dents to the sheet metal body panels and shattered glass, especially on side windows and sunroofs. Wind-driven hail can intensify this damage, sometimes resulting in total loss for an exposed car.
Structural damage to homes and commercial buildings is extensive, most notably affecting roofing materials. Hailstones compromise the integrity of asphalt shingles by dislodging protective mineral granules, which accelerates wear and exposes the underlying matting to the elements. Larger hail can fracture wood shingles, dent metal gutters and downspouts, puncture siding, or break windows, leading to water intrusion.
The economic impact on agriculture is equally devastating, as a single hailstorm can wipe out an entire season’s work, resulting in total crop losses across thousands of acres. Hailstones strip foliage, bruise and puncture fruit, and shred the leaves of crops like corn, wheat, and soybeans, severely reducing or eliminating yield. Livestock caught in the open are also at risk of injury or death from large hailstones.
Essential Safety Procedures During a Storm
The most effective way to mitigate the danger of a hailstorm is to seek immediate shelter in a robust structure. If at home, move to an interior room on the lowest level, such as a basement or a windowless bathroom. Stay away from all windows, glass doors, and skylights. Drawing curtains or blinds can provide an extra layer of protection against flying glass should a window shatter from the impact.
If caught driving when hail begins to fall, pull over to a safe location away from traffic, but do not stop under an overpass or near trees that could fall. The vehicle’s metal frame offers the best protection, so remain inside. Angle the car so the hail hits the reinforced front windshield rather than the more fragile side windows. If no sturdy shelter is available outdoors, crouch down and use your arms or any available object to shield your head and neck.