CoCoRaHS Hail Week 2021


"CoCoRaHS Hail Week" -- April 11-17, 2021

Join us in creating 'Hail Awareness' during our annual "CoCoRaHS Hail Week". Most of us see hail in our backyards from time to time and many of us will even experience a hailstorm this month. Learn more about hail, including how to observe and report it, as we explore this icy phenomena all week long.

  • Monday: "Watch the CoCoRaHS animation on How to Measure Hail" This YouTube animation will help you prepare to measure hail in your yard. Hail Video
  • Tuesday: "Five things you always wanted to know about hail, but were afraid to ask" We will feature some interesting facts about those falling balls of ice.
  • Wednesday: "CoCoRaHS Hail Reports . . . What are they, how can I access them?" How you can help report hail.
  • Thursday: "CoCoRaHS Hail Pads" How to make a hail pad . . . it's fun and easy to do.
  • Friday: "CoCoRaHS Hail Photo Day" Have a great/unique photo of hail? E-mail it to us today!
  • Saturday/Sunday: "CoCoRaHS National ‘Put out your Hail Pad’ Weekend" Have a hail pad? . . . join thousands around the country who will put out their hail pads this weekend. It’s that time of year!

To find out more about hail, visit our CoCoRaHS Hail Page by clicking here: Hail Information


MONDAY: CoCoRaHS Animation on “How to Measure Hail”

Many folks have asked how do I record and measure hail? Our hail animation short will help you to be ready and know what to do when hail makes it’s occasional visit to your location.

To view our four minute animation click here


TUESDAY: "Five Interesting Facts About Those Frozen Balls of Ice"

Over the years CoCoRaHS has become one of few repositories of hail information in the nation. Thanks to your observations, we are able to catalogue hail reports from all fifty states. As we strive to become more 'hail aware' here are five things you may or may not know about hail.

1) Hail comes in many shapes and sizes, ranging from rice sized pellets (1/8") to giant softballs (4 1/2"). Hail can be clear or white or a combination of the two. Hail can be hard or soft. Wind patterns usually form hailstones into balls, but they can also appear in other shapes, such as cones, discs, stars, pyramids, or just strange looking pointy blobs. We've even had reports of donut shaped stones!

2) On July 23, 2010, the largest hailstone ever recorded in the United States in terms of diameter and weight fell in Vivian, South Dakota. The stone had a diameter of 8.0 inches with a circumference of 18.625 inches and weighed 1.9 pounds. No one was injured. This hailstone broke the previous United States hail size record for diameter (7.0 inches - 22 June 2003 in Aurora, NE) and weight (1.67 pounds - 3 September 1970 in Coffeyville, KS). The Aurora, Nebraska hailstone will retain the record for circumference (18.75 inches). 

3) In North America, hail is most common on the High Plains just east of the Rocky Mountains. For example where Colorado, Nebraska, and Wyoming's borders meet just east of Cheyenne, WY there are an average of 9 to 10 hailstorms each year. Hail in this region occurs between the months of March and October mostly during the afternoon and evening hours, with the bulk of the occurrences from May through September. 

4) Hail suppression has been tried by many over the years including silver iodide cloud seeding and types of rockets. "Hail cannons" whose "LOUD" acoustic burst is believed to break-up hail while it is just forming, are still being used in some areas where fruit and vegetables are grown extensively. 

5) Hail is found in many countries around the world, such as China. In June 1932 a hailstorm killed an estimated 200 people, and injured thousands more there. Other countries with frequent hailstorms include southern and western Germany, northern Italy, northern India and Croatia.



WEDNESDAY: CoCoRaHS Hail Reports . . . What are they, how can I access them?

Thanks so much for your CoCoRaHS hail reports. You may not realize it, but there are very few sources for accurate data about hail. Most weather stations don't even measure or report hail. Scientists have great difficulty finding good data to help analyze hail storm patterns, frequencies, probabilities, etc. Therefore, our CoCoRaHS hail reports are especially important. Check out CHILL Radar expert Pat Kennedy's article on the important role that CoCoRaHS observers can play during hailstorms.

If you experience hail at your location (even the small stuff) please use the CoCoRaHS hail report form to submit a report. Even if you don't have much information about the hail or weren't home to know exactly when it happened, still send in a report: Hail Report

Hail pads help us document the size and number of stones. If hail pads are not provided in your area, you can make your own: Making Hail Pads. More on this subject tomorrow!

Please report hail even if you don't have a CoCoRaHS hail pad: Measure Hail

"Days with Hail" reports are viewable to the public and include a list of all days during a calendar year with one or more hail reports entered into the CoCoRaHS database. This is a great way to see where hail fell across the country on any given day as well as the size of the hailstones. Those reports with a camera icon next to them indicate that a photo of a hail pad associated with that specific report is available for viewing on-line.

To access the "Days with Hail" report click "View Data" on the CoCoRaHS homepage's top menu bar. Under "Summary Reports" click "Days with Hail Reports". That's all there is to it.

You can also see a map of hail reports for any given day by clicking here: Hail Maps



THURSDAY:"CoCoRaHS Hail Pads" -- How to make a hail pad . . . make your own at home!

Hail pads are essential to CoCoRaHS's mission to measure, map and study hail. They are fairly easy to construct with the right materials. If you can wrap a present, you can most likely make a hail pad.

A hail pad consists of a 12" by 12" square of Styrofoam covered in heavy duty aluminum foil. A little tape and you're set to go. To learn more on how to construct one visit: Making Hail Pads.

For those of you who would like to order hail pads without going through the process of making your own, they are available from for a modest fee. 


FRIDAY:"CoCoRaHS Hail Photo Day"

Do you have a great/unique photo of hail that you observed within the last year? E-mail it to us today! We hope to use these in our presentations and educational information on hail.

The categories of photos we are looking for are: 1) close-up photos of hail stones -- unique shapes, size, colors, etc.; 2) hail damage (vegetation, dented cars, etc.) showing the power of this force of nature; and 3) interesting shots of ground covered by hail. For your safety, please wait until the storm is over to take your photos.

Send your hail photos over the next several weeks to: Please include the name of the photographer for credit purposes, the date of the hail, as well as the location - city, state - of where the hail fell (ex- Billy James, April 4, 2019, Raleigh, NC). Without this information, we will not be able to use your photo. Finally please include in the text of your message that "you give CoCoRaHS permission to publish the photo and use it for other possible CoCoRaHS promotions".


SATURDAY/SUNDAY: CoCoRaHS National "Put out your Hail Pad Weekend"

Have a hail pad? . . . join hundreds around the country who will put out their hail pads this weekend. It's that time of year!

We have a saying in CoCoRaHS and that is "A hail pad does no good unless it's outside to capture the footprint of a hail storm as it passes overhead". This is so true! Many of us from time to time will learn of a hail event hitting our neighborhood while we are at work, out shopping, etc. and say to ourselves, "Great! Guess where my hail pad is . . . it's in the garage!" When our pads are out and deployed it is really fun to see the actual craters hail has left on the pad after the storm. Many pads often look like the surface of the moon. So don't miss out, put your hail pad out on this special "Put out your Hail Pad Weekend".

Some have asked, "Gee, these pads are light, how do we keep them from blowing away?" Great question! A simple way would be to cut two "L" shaped wires from a metal coat hanger and secure the pad to the ground in that fashion. Others have attached them to their snow measuring boards or made a special 18" x 18" plywood board to attach them to. Still others have mounted them to old tree stumps. As long as you have an open area with an exposure to the sky and not too close to a building you will be fine. Some have chosen to elevate their pads to prevent their pets from stepping on them. Many have sprayed a dull coat of spray paint on the pad to keep birds from peeling them and using the foil for nest material (somehow many birds are attracted to the shine of the metal). It is also important to mark an "N" on the back of your pad to tell which direction is north. Finally, make sure to include your station ID number on the back of the pad and the date the hail event occurred. We get many amazing looking pads dented with craters, but unfortunately with no information on them.

We often are asked the question, "Can the foam be reused or recycled?" The answer is yes . . . when we make hail pads here in Colorado, we are careful to reuse the foam (after the pad is photographed and analyzed) if it is still intact by turning it over to make a new pad. You can do this too if you decide to photograph and not send the pad in to us. If the pad is too far gone, please check locally to see if you can recycle the foam.

Also, please remember that you do not need to have a hail pad to report hail that falls in your yard. You can report it by clicking here: Hail Report.

Thanks again for joining us for "CoCoRaHS Hail Week". We will rerun some of this week's messages from time to time. We'd love to have your feedback as to whether this series was helpful in making you more "hail aware". Send your thoughts to: .

Have a great weekend and thanks for putting out your pad!