Weather on September 21 at Rocky Mountain
Rocky Mountain National Park
Based on 54 years of data from Estes Park, CO
Elevation Note: Rocky Mountain sits at 8,000 ft. Expect temperatures 28°F cooler than the data shown below, which comes from Estes Park, CO at a lower elevation.
Planning Your Visit
September 21st in Rocky Mountain National Park (via Estes Park, CO) typically brings mild fall weather, with average highs around 66°F and lows near 36°F — a 30°F daily swing. Over 54 years of records, the warmest September 21st was in 2005 (69°F average), while the coldest was 1999 (34°F) — a 35°F range across recorded history. Precipitation has occurred on 28% of recorded September 21st dates, with snow falling 4% of the time (heaviest snowfall: 8.3"). The last decade has been 8.5°F warmer on this date compared to 20-30 years ago.
The last decade has been 8.5°F warmer on this date compared to 20-30 years ago.
Planning for September 21st in Rocky Mountain? Great weather for outdoor activities.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 71°F | 44°F | 0" | -- |
| 2024 | 79°F | 35°F | 0" | 0" |
| 2023 | 70°F | 36°F | 0" | 0" |
| 2022 | 79°F | 51°F | 0" | 0" |
| 2021 | 59°F | 24°F | -- | -- |
| 2020 | 72°F | 39°F | 0" | 0" |
| 2019 | 74°F | 45°F | 0" | 0" |
| 2018 | 70°F | 32°F | 0" | 0" |
| 2017 | 70°F | 40°F | 0" | 0" |
| 2016 | 75°F | 57°F | 0" | 0" |
| 2015 | 73°F | 46°F | 0" | 0" |
| 2014 | 72°F | 43°F | 0" | 0" |
| 2013 | 62°F | 33°F | 0" | 0" |
| 2012 | 71°F | 38°F | 0" | 0" |
| 2011 | 58°F | 32°F | 0" | 0" |
| 2010 | 77°F | 43°F | 0.03" | 0" |
| 2009 | 67°F | 37°F | 0.03" | 0" |
| 2008 | 66°F | 36°F | 0.43" | 0" |
| 2007 | 73°F | 39°F | 0" | 0" |
| 2006 | 64°F | 40°F | 0.36" | 0" |
| 2005 | 79°F | 59°F | 0" | 0" |
| 2004 | 64°F | 36°F | 0.74" | 0" |
| 2003 | 66°F | 31°F | 0" | 0" |
| 2002 | 69°F | 38°F | 0" | 0" |
| 2001 | 74°F | 41°F | 0" | 0" |
| 2000 | 52°F | 31°F | 0" | 0" |
| 1999 | 43°F | 26°F | 0.3" | 0" |
| 1998 | 54°F | 29°F | 0.15" | 0" |
| 1997 | 42°F | 33°F | 0.25" | 0" |
| 1996 | 55°F | 35°F | 0" | 0" |
| 1995 | 54°F | 19°F | 2.62" | 8.3" |
| 1994 | 55°F | 17°F | 0.64" | 2" |
| 1993 | 73°F | 38°F | 0" | 0" |
| 1992 | 65°F | 49°F | 0" | 0" |
| 1991 | 73°F | 35°F | 0" | 0" |
| 1990 | 64°F | 36°F | 0" | 0" |
| 1989 | 59°F | 40°F | 0.15" | 0" |
| 1988 | 73°F | 40°F | 0" | 0" |
| 1987 | 61°F | 28°F | 0" | 0" |
| 1986 | 69°F | 34°F | 0" | 0" |
| 1984 | 71°F | 46°F | 0.05" | 0" |
| 1983 | 63°F | 23°F | 0" | 0" |
| 1982 | 68°F | 35°F | 0.05" | 0" |
| 1981 | 75°F | 46°F | 0" | 0" |
| 1980 | 68°F | 34°F | 0" | 0" |
| 1979 | 66°F | 36°F | 0.28" | 0" |
| 1978 | 58°F | 20°F | 0" | 0" |
| 1977 | 71°F | 30°F | 0" | 0" |
| 1976 | 64°F | 33°F | 0" | 0" |
| 1975 | 56°F | 26°F | 0" | 0" |
| 1974 | 57°F | 37°F | 0" | 0" |
| 1973 | 77°F | 49°F | 0" | 0" |
| 1972 | 66°F | 29°F | 0" | 0" |
| 1971 | 54°F | 30°F | 0.36" | 0" |