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What the hail?! Explaining different hail sizes

Katie McGraw explains different hail sizes and how to measure them correctly

By: Katie McGraw

Posted at 8:14 AM, Apr 13, 2023

and last updated 2023-04-13 08:14:36-04

Hail is frozen precipitation that can grow to very large sizes through the collection of water that freezes onto the hailstone’s surface. Hailstones begin as embryos, which include graupel or sleet, and then grow in size. Hailstones can have a variety of shapes and include lumps and bumps that may even take the shape of small spikes. Hailstones must be at least 0.2 inches in size. You can read more about how hail is formed here or watch below.

How hail forms and why it can be dangerous

Hail size is often estimated by comparing it to a known object. Most hailstorms are made up of a mix of different sizes, and only the very largest hail stones pose a serious risk to people caught in the open. When reporting hail, estimates comparing the hail to a known object with a definite size are good, but measurements using a ruler, calipers, or a tape measure are best. Below is a list of sizes. Hail is considered severe when it falls with a 1-inch diameter or more.

Pea = 1/4 inch diameter
Mothball = 1/2 inch diameter
Penny = 3/4 inch diameter
Nickel = 7/8 inch
Quarter = 1 inch — hail quarter size or larger is considered severe
Ping-Pong Ball = 1 1/2 inch
Golf Ball = 1 3/4 inches
Tennis Ball = 2 1/2 inches
Baseball = 2 3/4 inches
Tea cup = 3 inches
Softball = 4 inches
Grapefruit = 4 1/2 inches

The largest hailstone recovered in the United States fell in Vivian, South Dakota, on June 23, 2010, with a diameter of 8 inches and a circumference of 18.62 inches! It weighed 1 lb 15 oz. If you ever want to report hail during a storm to the National Weather Service, you can do so at this link.