On January 28, 1887, something remarkable was reported at Fort Keogh, Montana—a snowfall of giant proportions. Observers claimed to have witnessed snowflakes as large as 15 inches wide falling from the sky, marking what is often considered the largest recorded snowflake event in history.

The story of these enormous snowflakes has sparked curiosity and debate for generations, blending meteorological fascination with a touch of mystery. While the existence of such large snowflakes seems unusual, scientific theories suggest that under certain wet and heavy snow conditions, the formation of giant flakes is possible.

The Discovery of the “Giant Snowflakes” at Fort Keogh

In 1887, Fort Keogh in Montana became the site of a remarkable weather phenomenon involving unusually large snowflakes. These events captured the attention of the public and the scientific community, raising questions about how such giant snowflakes could form and whether the reports were accurate.

Historical Context of Fort Keogh

Fort Keogh was a military post established in Montana during the late 19th century. Its location in the northern plains meant it routinely experienced harsh winters and significant snowfall. Soldiers and settlers residing there were accustomed to reporting unusual weather events due to the exposed landscape and fluctuating conditions.

The winter of 1887 brought an exceptionally wet and heavy snowstorm. During this period, observers at the fort recorded not just the usual snow, but also snowflakes of remarkable size and shape. The nature of the storm, with a combination of moisture and particular atmospheric conditions, allowed for the formation of unusually large flakes not commonly seen elsewhere in the region.

Eyewitness Accounts and Initial Reports

On January 28, 1887, eyewitnesses at Fort Keogh claimed to see snowflakes as large as 15 inches (38 centimeters) across. These reports were made by soldiers and other residents, who described the snowflakes as being “as big as milk pans.” Such descriptions appeared in newspapers and later weather records, with some contemporary scientists expressing skepticism but others attempting to analyze the physical conditions behind the phenomenon.

Eyewitness accounts described the flakes as wet and fragile, falling slowly to the ground. Some observers noted the presence of clusters of flakes loosely bound together, possibly contributing to the perceived size. The story of the Fort Keogh giant snowflakes has endured in weather history books and remains a subject of curiosity for meteorologists and laypersons alike.

Scientific Analysis of Giant Snowflakes

Reports of giant snowflakes, such as those at Fort Keogh, have prompted detailed examination by meteorologists. The unique properties and formation of these unusually large snowflakes set them apart from the typical crystals observed in winter weather.

Physical Characteristics of Large Snowflakes

Large snowflakes are significantly bigger than the average, with some historical reports describing diameters of up to 15 inches. These giant snowflakes are often fragile and can break apart easily due to their size and structure.

Typical snowflakes form as hexagonal plates or dendrites, but giant snowflakes result from the aggregation of many smaller flakes. Their texture is usually more irregular, combining overlapping and loosely bonded crystals.

Some physical traits of large snowflakes:

Diameter: Up to 15 inches (unconfirmed record; most are 2–5 inches)
Structure: Irregular, composed of multiple bonded flakes
Density: Lower than compact snow crystals
Stability: Prone to breakage in transit

These characteristics make large snowflakes a rare observation.

How Giant Snowflakes Form

The process behind the formation of giant snowflakes involves very specific atmospheric conditions. High humidity and temperatures close to freezing allow snow crystals to remain sticky, enabling them to clump together as they fall.

Gentle winds are important to minimize breakage as the snowflakes descend. Calm, moist air favors the aggregation process, while stronger winds can prevent formation and break up large crystals.

Key factors in giant snowflake formation:

High humidity enhances crystal aggregation.
Temperatures just below freezing help snowflakes stick together.
Minimal air turbulence preserves the integrity of the large flakes.

Such conditions are rare, contributing to the infrequency of verified giant snowflake events like the one reported at Fort Keogh.

Record-Breaking Snowfall at Fort Keogh

A snowstorm in Montana during the 19th century resulted in what is widely regarded as one of the most unusual meteorological events ever recorded. This event brought worldwide attention due to the unprecedented size of snowflakes reported in the region.

Details of the Notable Snowstorm

In January 1887, Fort Keogh, near Miles City, Montana, experienced a significant snowstorm. Soldiers and residents of the fort reportedly witnessed snowflakes of remarkable size falling to the ground.

Eyewitness accounts described individual snowflakes as measuring up to 15 inches (38 centimeters) across. The atmospheric conditions at the time were thought to be ideal for flake formation, with high humidity and temperatures hovering near freezing.

Heavy, wet snow tends to encourage the fusion of smaller ice crystals, which can result in very large composite flakes. Scientists theorize that slow wind speeds and abundant moisture contributed to the phenomenon at Fort Keogh.

World Records for Largest Snowflakes

According to the Guinness World Records, the largest snowflakes ever observed reportedly fell at Fort Keogh, Montana, in 1887. The flakes measured up to 15 inches wide and 8 inches thick, making them the largest documented in meteorological history.

A summary of record details:

Attribute Measurement Location Year Width Up to 15 inches Fort Keogh, MT 1887 Thickness Up to 8 inches Fort Keogh, MT 1887

Modern scientific analysis supports the possibility of large snowflakes under specific conditions, but the Fort Keogh event remains exceptional in its documented scale. Climate and precipitation trends have not produced comparable reports in recent times.

Comparison to Other Large Snowflakes

Reports of giant snowflakes at Fort Keogh prompt questions about how these flakes stack up against other historic sightings. Snowflakes with unusual size and structure have been observed in various regions and under different weather conditions.

Similar Events Worldwide

Throughout history, unusually large snowflakes have been recorded in locations outside Montana. In the 19th century, for example, multiple observers in the United States and the United Kingdom reported snowflakes with diameters larger than two inches. Some accounts described the flakes as fragile, often breaking apart before anyone could measure them precisely.

Notably, London experienced a snowfall in the 1880s where flakes reportedly clustered into patches several inches wide. In areas of Canada and Russia, locals also recall “blanket-like” flakes during wet snowstorms. Weather scientists believe such large flakes typically form when warmer, moist air allows individual snow crystals to bind together.

Eyewitness reports are often inconsistent and rarely supported by photographs. Meteorologists caution that without direct measurement, many old accounts remain anecdotal. Nonetheless, repeated stories from various continents show that exceptional snowflake sizes are not limited to one region.

Snowflake Size Versus Frisbee

The snowflakes at Fort Keogh in 1887 were said to be up to 15 inches wide, about the diameter of a modern frisbee. Most snowflakes observed today are far smaller, averaging just a few millimeters in diameter.

Snowflake Type Size Range Example Typical Snowflake 2–5 mm (0.1–0.2 in) U.S., Canada Large Snowflake Up to 2-4 in UK, Russia Fort Keogh “Giant” Up to 15 in Montana, 1887 Frisbee 8-11 in Modern toy

Measurements show that no scientifically verified snowflake has ever equaled or exceeded the “giant” size from Fort Keogh. The story remains unmatched in the record books for both its scale and the number of eyewitnesses.

Modern weather reports continue to describe occasional large snowflakes, but none have reliably matched the frisbee-sized proportions seen in Montana. This makes the Fort Keogh event a lasting point of curiosity among meteorologists.

Impact and Legacy of the Fort Keogh Giant Snowflakes

The 1887 report of unusually large snowflakes at Fort Keogh left both scientific and cultural marks. This event inspired debate in meteorology and became a memorable story in Montana’s local history.

Influence on Snowfall Research

Reports from Fort Keogh described snowflakes up to 15 inches wide. This account led meteorologists and weather historians to reconsider the limits of snowflake formation.

Skepticism is common—many researchers question whether snowflakes of that size could form naturally. However, the Fort Keogh observation encouraged further study. Scientists analyze atmospheric conditions that produce unusually large flakes, looking at humidity, temperature, and aggregation.

Though direct evidence remains debated, the Fort Keogh incident remains a reference point. It highlights the unpredictability and variety found in Montana’s snowfall and the broader study of snow crystals.

Cultural Significance in Montana

Locally, the story of the Fort Keogh giant snowflakes has become part of Montana folklore. It is frequently referenced in books, articles, and community events.

For residents in the region, this peculiar weather event is more than a scientific anomaly. It represents the wild, unpredictable nature of Montana winters and fosters a sense of identity connected to unique local stories.

While its veracity is still questioned, the tale endures. It is recounted as an example of the extremes possible in the region’s climate, illustrating how natural events can shape cultural memory.

The Giant Snowflakes of Fort Keogh Largest Recorded Snowfall in History