High-Impact Weather and Climate Events

High-impact events cause the majority of societal costs related to weather and climate. They provoke societal responses that can either enhance or detract from long-term adaptation to climate risk. In 2015, WWA began a new research focus on extremes that is designed to place high-impact events in the context of historical climate variability and projected climate change, assess how the risk of these events varies over time and space, and examine how high-impact events interact with place-based vulnerability.

The High-Impact Events Database has 280+ historical high-impact weather and climate events in our three-state region, and a complementary set of regional event maps showing how risk varies seasonally across the region for different types of weather and climate events.

The database is a curated collection of significant weather and climate-related events in the Western Water Assessment region. The types of events included are: avalanches, cold waves, dam failures, droughts, floods, hail, high winds, landslides, tornadoes, wildfires, and winter storms. We search federal, state, county, and local databases, library archives, news accounts, and other sources for current and historic notable weather and climate-related events in Colorado, Utah, and Wyoming. This database is not a scientific collection of extreme events. The majority of events included in this database are incidents that were identified as remarkable by one of the sources listed above.

All CPI-Adjusted Damage costs are 2022 values, calculated from: https://www.usinflationcalculator.com/. CPI-Adjusted Damage costs are unavailable before the year 1913.

WWA High-Impact Events Database Map (1864-2021)

This map is a visual representation of all the high-impact events in our database by county from 1864-2021. The counties with no data represent counties with no events explicitly reported in the database.

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State	County	City	Date	Event Type	Deaths	CPI Adjusted	Unadjusted
Utah	Garfield	Hatch	May 25, 1914	Dam Failure		$14,000,000.00
Colorado	Larimer, Denver, Boulder, Clear Creek, Jefferson		December 01, 1913	Winter Storm				Summary Huge upslope snow event impacted much of Front Range; 46" storm total for Denver is still the all-time record-largest snowstorm, 86" in Georgetown. Denver was brought to a standstill. "There were 45.7 inches of snow on the ground in Denver on December 5, 1913. For four days, a massive blizzard hit Colorado. It remains the largest snowstorm recorded in Denver's history. According to the Denver Public Library, the snow began on Dec. 1 and continued through Dec. 5, leaving the city blanketed under more than 3.5 feet of snow. History Colorado Center said schools and businesses were closed for days and some residents even slept at work because they were unable to get home." - 9News
Colorado	Denver, Douglas	Denver, Franktown, Parker	July 14, 1912	Flood	2		$2,000,000.00	Summary $47,698,400 (2017 dollars). Centered over Sullivan, a cloudburst caused flooding on Cherry Creek and surrounding drainages. A wall of water 30 feet high rolled down Cherry Creek, shattering the retaining walls on the creek. Affecting Denver, Franktown, and Parker, the water was 3 feet high in some places. Two lives were lost.
Wyoming	Johnson		June 11, 1912	Flood
Colorado	La Plata, San Miguel, Huerfano, Rio Grande, Alamosa	Durango, Telluride, Del Norte, Monte Vista, Walsenburg	October 05, 1911	Flood	3		$1,000,000.00
Colorado	Denver	Denver	October 20, 1906	Winter Storm
Colorado	San Juan	Howardsville	March 17, 1906	Avalanche	12			Summary "In the early evening hours, the Shenandoah bunk house and boarding house were destroyed in this slide. Twenty-one men were in the boarding house eating dinner; only nine survived. In the Silverton Standard newspaper, the buildings were described by a survivor as being "smashed" into "kindling wood," with the men "all thrown out into the slide at one time."" - 9News
Wyoming	Natrona	Casper	March 01, 1906	Dam Failure, Flood	12			Summary "On March 1, 1906, flooding along the North Platte River near Casper resulting from snow/ice melt caused a diversion dam to fail. A stream returned to its natural channel with a culvert too small to handle the flood, causing the water to rise against a railroad embankment. The embankment failed. Twelve were killed in a train wreck when the railroad bridge was damaged." - WY Hazard Mitigation Plan 2021-2026
Colorado	Las Animas	Trinidad, Tabasco, Berwind	August 25, 1905	Flood	35		$100,000.00
Colorado	Pueblo	Pueblo, Eden	August 07, 1904	Flood	111

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High-Impact Weather and Climate Events

WWA High-Impact Events Database Map (1864-2021)

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