Peak Hail Season Is Here. Get the Facts Right.

Hail causes more property damage in the United States each year than any other thunderstorm hazard — more than tornadoes, more than lightning, more than straight-line winds. Insurance industry data consistently puts annual hail damage in the billions of dollars, and the peak of the hail damage season runs squarely through May and June across the central and eastern United States.

Despite its frequency and cost, hail is poorly understood by most people. The myths surrounding it range from harmless misconceptions to dangerous beliefs that cause people to make bad decisions during storms. May is the right time to address them.

Myth: Hail Only Falls During Severe Thunderstorms

Hail can fall from any thunderstorm capable of producing strong updrafts — not just those that reach the severe criteria of 58 mph winds or a tornado. The severe thunderstorm threshold for hail, defined by the National Weather Service as one inch in diameter, is a warning trigger, not a threshold for hail occurrence. Hail smaller than one inch falls frequently from ordinary thunderstorms that generate no warnings at all.

Small hail — pea-sized or smaller — is common in run-of-the-mill springtime thunderstorms and rarely causes significant damage. But it can accumulate rapidly and create hazardous driving conditions, and it’s a reminder that the absence of a severe thunderstorm warning doesn’t mean hail isn’t falling. Conversely, severe thunderstorm warnings specifically for hail indicate stones large enough to cause property damage and injury, which are the events that warrant taking cover.

Myth: Hail Forms When Raindrops Freeze Falling Through Cold Air

This is the most common misconception about how hail forms, and it gets the process almost entirely backward. Hail doesn’t form by freezing on the way down — it forms by growing on the way up, repeatedly, inside a thunderstorm’s updraft.

The process begins when a small ice particle — a frozen raindrop or an ice crystal — gets caught in a thunderstorm’s updraft and carried upward into the subfreezing upper regions of the storm. As it rises, it collides with supercooled water droplets — liquid water that remains unfrozen despite being below 32°F — that freeze onto its surface, adding a layer of ice. Wind carries the growing stone up and down through the storm, adding layers with each pass through the region of supercooled water. When the hailstone becomes heavy enough that its fall speed exceeds the updraft speed, it falls to the ground.

The size of hail is directly related to the strength of the updraft. A stronger updraft keeps hailstones aloft longer, allowing more growth cycles and larger final size. The most violent supercell thunderstorms — the ones with updraft speeds exceeding 100 mph — are capable of producing baseball-sized or larger hail because they can support the weight of very large stones against the pull of gravity.

Cutting a hailstone in cross-section reveals concentric rings of clear and opaque ice — each ring representing one growth cycle through the updraft. The number of rings indicates how many times the stone cycled through the storm before finally falling.

Myth: Larger Hail Falls Faster and Hits Harder

This is partially true but significantly more complicated than it seems, and the complication matters for understanding hail damage.

Larger hailstones do fall faster than smaller ones because their greater mass relative to their cross-sectional area gives them a higher terminal velocity. A golf-ball-sized hailstone falls at roughly 60 to 70 mph. A baseball-sized stone may exceed 80 mph. But hailstones don’t fall in a vacuum — they fall through air that is often moving, and thunderstorm downdrafts can add substantially to a stone’s effective impact speed.

The more important variable for damage is the combination of size, speed, and shape. Hailstones are not smooth spheres — they are often irregular, with protrusions, rough surfaces, and sometimes spiky shapes resulting from their complex formation history. An irregular stone of a given size and speed causes more damage than a smooth sphere of the same parameters because the energy of impact is concentrated on a smaller contact area. This is why hail damage assessments focus on stone size as a proxy but actual damage depends on many variables that size alone doesn’t capture.

Wind during hail events adds another significant variable. Hail falling in a strong thunderstorm outflow wind strikes surfaces at an angle rather than vertically, which affects where and how damage occurs on structures. Horizontal hail — stones driven nearly sideways by strong winds — can penetrate window screens, damage siding, and break windows in ways that vertically falling hail of the same size would not.

Myth: Your Car Provides Safe Shelter From Hail

A car provides better shelter from hail than standing in the open, but it is not safe shelter in the sense that most people assume. The roof, hood, and trunk of a standard vehicle will dent significantly in large hail, and the windows — particularly the windshield — can crack or shatter in hail above golf ball size.

If you are caught in large hail while driving, pull over and stop — driving during large hail is dangerous because the noise on the roof and windshield is disorienting and visibility drops rapidly. Pull away from trees that could shed branches, and if the hail is severe enough to threaten windshield integrity, lean away from the glass and protect your face and head. Lying down on the floorboard with your back toward any windows provides the best protection if you believe glass breakage is imminent.

Seeking shelter under an overpass during a hail event is tempting but should be avoided for the same reasons discussed in the tornado myths piece — overpasses concentrate wind and debris rather than providing protection, and hail driven by storm outflow winds is no exception.

The best shelter during large hail is inside a substantial building, away from windows. If you have advance warning of large hail — which modern radar can frequently provide — getting your vehicle into a garage or under substantial cover before the storm arrives is far preferable to any in-storm response.

Myth: Hail Damage to Your Roof Is Always Obvious

This is one of the most practically significant hail myths because it directly affects how homeowners respond — or fail to respond — after a hail event.

Visible hail damage — dented gutters, cracked skylight covers, damage to air conditioning units, dimpled car hoods — is apparent immediately after a storm. Roof damage from hail is frequently invisible from the ground and sometimes invisible even on close inspection by an untrained eye. Hailstone impacts on asphalt shingles create impact points that displace the granules — the tiny stone particles embedded in the shingle surface — exposing the underlying asphalt mat. This granule loss isn’t a cosmetic issue; the granules protect the asphalt from UV degradation, and their displacement accelerates shingle deterioration dramatically.

Hail-damaged shingles may look normal from the ground and even from a casual rooftop inspection but fail within months to a few years as the exposed asphalt dries and cracks. By the time water infiltration becomes apparent inside the house, the damage has been progressing for some time.

After any hail event with stones above quarter size — roughly an inch in diameter — have your roof inspected by a qualified roofing contractor or public adjuster. Document the hail event with dated photographs of ground-level damage. Insurance claims for hail damage have time limits, and hail damage that isn’t identified and reported promptly may not be covered by the time it manifests as a leak.

Myth: Hail Is Rare in My Area

Hail frequency is higher and more geographically widespread than most people realize. The highest frequency hail region in the country is the central Great Plains — a corridor sometimes called “Hail Alley” running through eastern Colorado, western Kansas, and Nebraska — but significant hail events occur regularly across the entire central and eastern United States.

The Midwest, Ohio Valley, and mid-Atlantic states all experience multiple significant hail events per year in most years. Even the Southeast, which has a lower hail frequency than the Plains, sees damaging hail events regularly. Only the Pacific Coast states, parts of the mountainous West, and the Gulf Coast have substantially lower hail frequency than the rest of the country.

More importantly, hail frequency statistics describe averages — any given location may experience its worst hail event in a century on any given May afternoon. Hail damage preparedness is appropriate for any location east of the Rockies, not just for communities that have recently experienced damage.

What Actually Protects You

The most effective hail protection measures are the unglamorous ones: keeping vehicles in garages during hail season rather than leaving them outdoors overnight, maintaining roofs in good condition so hail impacts have less effect on already-compromised shingles, knowing what a severe thunderstorm warning means and getting inside when one is issued, and having your roof inspected promptly after significant hail events rather than assuming damage didn’t occur.

Hail’s predictability — it reliably forms in the strongest thunderstorms, in the most active severe weather months, in the regions of the country with the most organized storm activity — means that preparation before storm season and response after events are both within reach. The myth that hail is random, invisible in its damage, or safely weathered in a car are the beliefs that turn a storm that damages property into one that damages people.