Hail may seem like a sudden and surprising weather event, but the science behind it is both fascinating and important, especially as storms are becoming more common. From how hail forms to how climate change may be influencing its size and frequency, here’s what you need to know.

Hail most commonly forms during thunderstorms and periods of warmer weather. As warm surface air rises, strong updrafts pull raindrops upward into colder layers of the atmosphere. In these frigid zones, the droplets freeze into small balls of ice.

As the storm continues, these ice particles may be lifted repeatedly by the updraft, collecting additional layers of ice with each pass. When the hailstones grow too heavy for the updraft to support, gravity takes over, and they fall to the ground. This is the hail we experience on the surface.

The size of hailstones is directly linked to the strength and longevity of the storm’s updraft.

This is why some storms produce pea-sized hail while others may generate hailstones as large as golf balls or even softballs.

Hail season in the United States can stretch anywhere from February through September, a period when warm temperatures fuel frequent thunderstorms. During these warmer months, the freezing level within storm clouds is lower, making it easier for hailstones to form and survive the journey to the ground before melting.

While hail can occur outside this window, spring and early summer remain the peak times due to ideal atmospheric conditions.

Hail is most frequent in the Midwest and Great Plains, an area often referred to as “Hail Alley.” This region experiences a unique collision of air masses:

This meeting of contrasting air types creates the atmospheric instability needed for strong thunderstorms. Additionally, the higher elevation of the Great Plains keeps the freezing layer of the atmosphere closer to the ground, making hail formation even more likely.

As climate change accelerates, its influence on severe weather, including hailstorms, is becoming more evident. Warmer temperatures increase the amount of water vapor in the atmosphere, providing more fuel for thunderstorms and boosting the potential for heavy precipitation.

Additionally, a study from Northern Illinois University suggests that rising temperatures can strengthen storm updrafts, which in turn allows hailstones to grow larger. At the same time, higher melting levels in the atmosphere mean smaller hailstones are more likely to melt before reaching the ground, while larger hailstones survive the fall.

The possible result? Hail events may become less frequent, but the hail that reaches the ground is projected to be larger and more severe, which could lead to greater property damage, agricultural losses, and increased insurance claims.

Although scientists are gaining a deeper understanding of how climate change may influence hail, significant uncertainty remains. Long-term hail records are limited, as hailstorms tend to be small, localized events that often go unreported. Additionally, much of our current knowledge relies on computer models, which incorporate varying assumptions about future greenhouse-gas emissions and atmospheric behavior. Consequently, model results do not always align perfectly.

The best we can do as homeowners is to be educated and prepared when hail storms do hit. Want to be prepared for the upcoming hail season? Check out our article about how to protect your roof from scams!

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