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Understanding Hail Forecasts: A Comprehensive Guide

June 18, 2026 · The Clime Team
Understanding Hail Forecasts: A Comprehensive Guide

Hailstorms can cause significant damage to property, crops, and vehicles. Understanding how hail forms, how to interpret hail forecasts, and how to stay safe during hailstorms is essential for residents in hail-prone areas. This guide provides a comprehensive overview to help you stay informed and prepared.

What Is Hail and How Does It Form?

Hail is precipitation in the form of small ice balls or pieces, with diameters ranging from 5 mm (about 0.2 inch) to over 15 cm (about 6 inches). (earthnetworks.com)

Hail forms within strong thunderstorms when updrafts carry raindrops into extremely cold areas of the atmosphere, causing them to freeze. These frozen particles can then collide with supercooled water droplets, accumulating layers of ice and growing larger before falling to the ground. (nssl.noaa.gov)

How to Interpret Hail Forecasts

Hail forecasts are typically issued by the National Weather Service (NWS) and are based on the likelihood of hail occurring in a specific area. The NWS uses a color-coded system to indicate the probability of hail:

  • Brown/Gold Outline: 5% chance of hail
  • Dark Blue Outline: 15% chance of hail
  • Red Outline: 30% chance of hail

In rare cases, higher probabilities such as 45% or 60% may be indicated. (hailstormlocator.com)

Additionally, the Storm Prediction Center (SPC) provides severe weather outlooks that include hail risk assessments. These assessments are categorized as follows:

  • Marginal Risk (1 out of 5): Isolated severe thunderstorms possible
  • Slight Risk (2 out of 5): Scattered severe thunderstorms possible
  • Enhanced Risk (3 out of 5): Numerous severe thunderstorms possible
  • Moderate Risk (4 out of 5): Widespread severe thunderstorms expected
  • High Risk (5 out of 5): Widespread severe thunderstorms expected

Each category also includes an intensity level, indicating the potential severity of the storms. For example, a Level 1 intensity indicates the possibility of 2-inch or larger hail, while a Level 2 intensity indicates the possibility of 3.5-inch or larger hail. (iweathernet.com)

Hail Size Classification

Understanding the size of hailstones can help you assess potential damage:

  • Pea: 0.25 inches
  • Dime: 0.50 inches
  • Penny: 0.75 inches
  • Quarter: 1.00 inch
  • Half Dollar: 1.25 inches
  • Golf Ball: 1.75 inches
  • Tennis Ball: 2.50 inches
  • Baseball: 2.75 inches
  • Softball: 3.75 to 4.00 inches
  • Grapefruit: 4.75 inches

Hailstones 1 inch or larger are considered severe and can cause significant damage. (weather.gov)

How to Stay Safe During Hailstorms

To protect yourself and your property during hailstorms:

  • Seek Shelter: Move indoors or into a sturdy building. Avoid windows and doors.
  • Protect Vehicles: If possible, move vehicles into a garage or covered area. If not, cover them with a thick blanket or tarp.
  • Stay Informed: Monitor local weather updates and heed any warnings or advisories issued by the NWS.
  • Prepare Ahead: Have an emergency kit ready, including essentials like water, non-perishable food, and a flashlight.

Conclusion

Understanding hail formation, interpreting forecasts, and taking appropriate safety measures can significantly reduce the risks associated with hailstorms. Stay informed and prepared to protect yourself and your property.

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Frequently Asked Questions