Believe it or not, every county in Colorado has seen rain accumulate that originated from a tropical system. As we’ve seen recently with the flooding in New York City and the surrounding areas, even though a system is not deemed a tropical storm or hurricane doesn’t mean that it can’t still bring a huge amount of moisture with it as it continues its trek through the atmosphere.

There has never been a storm that has directly tracked over Colorado. We are pretty far inland so that checks out but we are close enough for remnants of tropical systems to reach us.

Since the 1880s, there have been 21 storms that have come within 300 miles of Colorado. Again, this is referencing the actual tracked line of a storm.

The official track of a tropical system ends when it loses all of its tropical characteristics – mainly a warm core and a closed surface low. However, tropical systems have a lot of energy with them and that energy can stay clumped together over large distances which is how we can end up with tropical rains. This was true with former Hurricane Nora which just brought us some rain recently.

Here is a list of how much rain has fallen in each county of Colorado since the 1880s that originated from a tropical system.

  • Adams County, CO – 3 to 4.99″ inches
  • Alamosa County, CO – 1 to 2.99″ inches
  • Arapahoe County, CO – 1 to 2.99″ inches
  • Archuleta County – 3 to 4.99″ inches
  • Baca County, CO – 3 to 4.99″ inches
  • Bent County, CO – 1 to 2.99″ inches
  • Boulder County, CO – 1 to 2.99″ inches
  • Broomfield County – 1 to 2.99″ inches
  • Chaffee County, CO – 1 to 2.99″ inches
  • Cheyenne County, CO – 1 to 2.99″ inches
  • Clear Creek County, CO – 1 to 2.99″ inches
  • Conejos County, CO – 3 to 4.99″ inches
  • Costilla County, CO – 1 to 2.99″ inches
  • Crowley County, CO – 1 to 2.99″ inches
  • Custer County, CO – 3 to 4.99″ inches
  • Delta County, CO – 1 to 2.99″ inches
  • Denver County, CO – 1 to 2.99″ inches
  • Dolores County, CO – 7 to 9.99″ inches
  • Douglas County, CO – 1 to 2.99″ inches
  • Eagle County, CO – 1 to 2.99″ inches
  • El Paso County, CO – 3 to 4.99″ inches
  • Elbert County, CO – 1 to 2.99″ inches
  • Fremont County, CO – 1 to 2.99″ inches
  • Garfield County, CO – 1 to 2.99″ inches
  • Gilpin County, CO – 1 to 2.99″ inches
  • Grand County, CO – 1 to 2.99″ inches
  • Gunnison County, CO – 3 to 4.99″ inches
  • Hinsdale County, CO – 3 to 4.99″ inches
  • Huerfano County, CO – 1 to 2.99″ inches
  • Jackson County, CO – 1 to 2.99″ inches
  • Jefferson County, CO – 3 to 4.99″ inches
  • Kiowa County, CO – 1 to 2.99″ inches
  • Kit Carson County, CO – 1 to 2.99″ inches
  • La Plata County, CO – 3 to 4.99″ inches
  • Lake County, CO – 1 to 2.99″ inches
  • Larimer County, CO – 1 to 2.99″ inches
  • Las Animas County, CO – 5 to 6.99″ inches
  • Lincoln County, CO – 3 to 4.99″ inches
  • Logan County, CO – 1 to 2.99″ inches
  • Mesa County, CO – 3 to 4.99″ inches
  • Mineral County, CO – 5 to 6.99″ inches
  • Moffat County, CO – 1 to 2.99″ inches
  • Montezuma County, CO – 3 to 4.99″ inches
  • Montrose County, CO – 1 to 2.99″ inches
  • Morgan County, CO – 3 to 4.99″ inches
  • Otero County, CO – 1 to 2.99″ inches
  • Ouray County, CO – 1 to 2.99″ inches
  • Park County, CO – 1 to 2.99″ inches
  • Phillips County, CO – 1 to 2.99″ inches
  • Pitkin County, CO – 1 to 2.99″ inches
  • Prowers County, CO – less than 1 inch
  • Pueblo County, CO – 1 to 2.99″ inches
  • Rio Blanco County, CO – 1 to 2.99″ inches
  • Rio Grande County, CO – 1 to 2.99″ inches
  • Routt County, CO – 1 to 2.99″ inches
  • Saguache County, CO – 1 to 2.99″ inches
  • San Juan County, CO – 3 to 4.99″ inches
  • San Miguel County, CO – 3 to 4.99″ inches
  • Sedgwick County, CO – 1 to 2.99″ inches
  • Summit County, CO – 1 to 2.99″ inches
  • Teller County, CO – 1 to 2.99″ inches
  • Washington County, CO – 3 to 4.99″ inches
  • Weld County, CO – 1 to 2.99″ inches
  • Yuma County, CO – 3 to 4.99″ inches

Tropical rains per county across the United States

Delores, Las Animas and Mineral counties have all seen more than 5 inches of rain from former tropical systems. Delores county in southwest Colorado sits at the top of the list for the most rain from a tropical system where more than 7 inches stacked up.

It’s hard to compile a list of the names of storms that have impacted Colorado but from looking at the tracks of former storms, we can infer which ones may have produced rains in Colorado.

  • Unnamed in 1886 (Atlantic)
  • Unnamed in 1932 (Gulf of Mexico)
  • Unnamed in 1942 (Atlantic)
  • Debra in 1959 (Gulf of Mexico)
  • Raymond in 1989 (Pacific)
  • Lester in 1992 (Pacific)
  • Nora in 1997 (Pacific)
  • Dolly in 2008 (Pacific)
  • Newton in 2016 (Pacific)
  • Nora in 2021 (Pacific)

This list is not all-inclusive but is an educated guess as to which storms have impacted us with rain. This year’s tropical originated moisture was the first time that Colorado has seen rain from a tropical system directly since 2016. While it is a rare occurrence to get tropical rains in Colorado, it does happen and will happen in the future too.

Leave a Reply

%d bloggers like this: