Weather on September 21
Fort Collins, CO
55 Years of Data
About This Date
September 21st in Fort Collins, CO typically brings pleasant fall weather, with average highs around 72°F and lows near 45°F — a 27°F daily swing. Over 56 years of records, the warmest September 21st was in 2007 (70°F average), while the coldest was 1995 (33°F) — a 37°F range across recorded history. Precipitation has occurred on 30% of recorded September 21st dates, with snow falling 2% of the time (heaviest snowfall: 5.6"). The last decade has been 6.9°F warmer on this date compared to 20-30 years ago.
The last decade has been 6.9°F warmer on this date compared to 20-30 years ago.
Planning for September 21st in Fort Collins, CO? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 74° | 46° | 60° | 0.01" | — |
| 2025 | 82° | 49° | 65° | — | — |
| 2024 | 73° | 58° | 65° | — | — |
| 2023 | 81° | 48° | 64° | — | — |
| 2022 | 75° | 51° | 63° | 0.2" | — |
| 2021 | 66° | 40° | 53° | 0.01" | — |
| 2020 | 82° | 47° | 64° | — | — |
| 2019 | 74° | 48° | 61° | — | — |
| 2018 | 76° | 48° | 62° | — | — |
| 2017 | 86° | 42° | 64° | — | — |
| 2016 | 84° | 56° | 70° | — | — |
| 2015 | 87° | 44° | 66° | — | — |
| 2014 | 72° | 58° | 65° | — | — |
| 2013 | 81° | 45° | 63° | — | — |
| 2012 | 80° | 44° | 62° | — | — |
| 2011 | 66° | 42° | 54° | — | — |
| 2010 | 74° | 51° | 62° | — | — |
| 2009 | 64° | 41° | 53° | 0.26" | — |
| 2008 | 76° | 55° | 65° | — | — |
| 2007warmest | 87° | 54° | 70° | — | — |
| 2006 | 66° | 52° | 59° | 0.05" | — |
| 2005 | 79° | 54° | 66° | 0.01" | — |
| 2004 | 56° | 42° | 49° | 0.67" | — |
| 2003 | 73° | 40° | 56° | — | — |
| 2002 | 67° | 43° | 55° | — | — |
| 2001 | 85° | 46° | 65° | — | — |
| 2000 | 68° | 39° | 54° | 0.02" | — |
| 1999 | 73° | 34° | 53° | — | — |
| 1998 | 59° | 46° | 53° | 0.24" | — |
| 1997 | 55° | 45° | 50° | 0.01" | — |
| 1996 | 77° | 39° | 58° | — | — |
| 1995coldest | 36° | 31° | 33° | 0.55" | 5.6" |
| 1994 | 65° | 35° | 50° | 0.17" | — |
| 1993 | 84° | 40° | 62° | — | — |
| 1992 | 74° | 55° | 64° | 0.01" | — |
| 1991 | 85° | 43° | 64° | — | — |
| 1990 | 68° | 49° | 58° | — | — |
| 1989 | 65° | 46° | 55° | 0.08" | — |
| 1988 | 77° | 49° | 63° | — | — |
| 1987 | 73° | 39° | 56° | — | — |
| 1986 | 68° | 47° | 57° | — | — |
| 1985 | 71° | 37° | 54° | — | — |
| 1984 | 82° | 51° | 67° | — | — |
| 1983 | 64° | 26° | 45° | — | — |
| 1982 | 72° | 45° | 58° | — | — |
| 1981 | 81° | 53° | 67° | 0.01" | — |
| 1980 | 81° | 44° | 62° | — | — |
| 1979 | 70° | 50° | 60° | 0.09" | — |
| 1978 | 63° | 32° | 47° | — | — |
| 1977 | 74° | 55° | 64° | — | — |
| 1976 | 72° | 45° | 58° | — | — |
| 1975 | 67° | 37° | 52° | — | — |
| 1974 | 63° | 38° | 50° | — | — |
| 1973 | 73° | 49° | 61° | — | — |
| 1972 | 70° | 37° | 53° | — | — |
| 1971 | 46° | 34° | 40° | 0.24" | — |
Fort Collins, CO Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Fort Collins, CO Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Fort Collins, CO Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit Fort Collins, CO
Most pleasant months in Fort Collins, CO: May, June, September.
What to expect on September 21st
This page shows what actually happened each year. For the odds — typical high and low, and how often it stays dry — see the climatological outlook for this date.
September 21st outlook →