This atlas of hailstorms across the nation has addressed
sed all the key aspects of the climatology of hail. The
key findings include:
-- The nation’s areas of greatest hail frequency are
along and just east of the central Rocky Mountains
where point averages vary from 6 to 12 hail days
-- The lee of the central Rocky Mountains has the
nation’s greatest hail intensity with the largest
average stone sizes, the greatest average
number of hailstones, and longest hail durations
when it hails.
-- The nation’s lowest hail intensities are found in
the southeastern U.S. (Florida), and in the southwest
(Arizona and California).
-- Winds with hail tend to be strongest in the central
and southern High Plains, making property-hail
intensity highest in an area including Nebraska,
Kansas, Oklahoma, and north Texas.
-- Hail risk to crops and property is characterized
by enormous variability in both space and time.
-- The risk of property damage across the nation
varies from a low value of 1 in the southeast to
a high of 50 (Colorado, Kansas), and the risk of
crop damage varies from a low of 1 in the eastern
Midwest and East to a high of 20 in the western
High Plains (Montana, Wyoming, and Colorado).
-- The intensity of hailfalls changes rapidly across
short distances, and average intensity values, and
risk of hail damage, significantly differ spatially
in most states.
-- Hail that is damaging to crops differs from that
damaging to property, in that various vulnerable
crops are damaged by small stones, whereas
property damage occurs only when hailstones
are 0.75 inch or larger.
-- Exceptionally large hailstones, those exceeding 2
inches in diameter, can occur anywhere it hails
in the U.S., but are most frequent in southeastern
Wyoming (once every five years) and least frequent
in the low hail frequency areas (only once every
100 years or less often at a given point).
-- There is great variation in the dimensions of hail
damage, with most damages occurring in 5 to 10
percent of all storms, and most losses occurring
in only a small fraction of an area experiencing
hail on a given date.
-- Time changes in hail frequency and crop-hail
intensity are quite large with a tendency for low
hail incidence in 60 to 80 percent of the years,
and exceptionally large losses in 5 to 15 percent
of the years.
-- The temporal variability of hail loss is greater
in the High Plains states than in states in the
Midwest, East, or West.
-- The magnitude and frequency of hail shifts up
and down randomly over time, but the primary
spatial features of hail (areas of extremely high
or low incidence of hail in a region) persist from
decade to decade.
-- Prediction of future trends in crop-hail losses for
individual states, as trending up or down over the
following three to five years, is accurate 80 percent
of the time.
-- Extremely damaging hailstorms to property
show an upward trend with time, and the two
most damaging storms in the U.S. occurred since
2000. The nationwide trends in crop-hail losses,
in property-hail losses, and in the number of hail
days all show downward trends for the 1950-present
-- Average annual hail losses are $852 million for
property and $581 million for crops, a national
total of $1.433 billion.
On going demographic shifts in the nation’s urban
areas with rapidly growing metropolitan areas have
increased the potential for costly losses from
hailstorms. During the 1951-1970 period, property
hail losses represented 46 percent of the nation’s
total hail losses (54 percent were crop losses). In
the 1981-2000 period, property losses grew and
exceeded crop-hail losses and had become 61 percent
of the of the national total losses to crops and
A storm in a rural area of Illinois is producing 1.5
inch hailstones and heavy rain. A hailstone has just
landed in the water in a roadside ditch, creating a
large splash (15 inches high), illustrating the force
of large hailstones.
For more hailstorm climatology for Colorado and across
the nation, click on the link below:
Hailstorms Across the Nation