Weather on September 1
Longmont, CO
55 Years of Data
Avg High
85°F
Avg Low
52°F
Warmest
2011
78°F avg
Coldest
1993
60°F avg
About This Date
September 1st in Longmont, CO typically brings warm fall weather, with average highs around 85°F and lows near 52°F — a 33°F daily swing. Over 55 years of records, the warmest September 1st was in 2011 (78°F average), while the coldest was 1993 (60°F) — a 18°F range across recorded history. Rain or other precipitation has occurred on about 29% of September 1st dates historically, with the wettest September 1st recording 1.32" of rain. The last decade has been 3.3°F warmer on this date compared to 20-30 years ago.
The last decade has been 3.3°F warmer on this date compared to 20-30 years ago.
Planning for September 1st in Longmont, CO? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
0.8°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 83° | 52° | 67° | — | — |
| 2024 | 88° | 53° | 70° | — | — |
| 2023 | 95° | 55° | 75° | — | — |
| 2022 | 91° | 54° | 72° | — | — |
| 2021 | 93° | 55° | 74° | — | — |
| 2020 | 74° | 46° | 60° | 0.2" | — |
| 2019 | 90° | 56° | 73° | — | — |
| 2018 | 90° | 56° | 73° | — | — |
| 2017 | 85° | 59° | 72° | — | — |
| 2016 | 85° | 51° | 68° | — | — |
| 2015 | 91° | 54° | 72° | — | — |
| 2014 | 84° | 46° | 65° | 0.03" | — |
| 2013 | 78° | 58° | 68° | 0.08" | — |
| 2012 | 87° | 57° | 72° | 0.2" | — |
| 2011warmest | 94° | 63° | 78° | 0.08" | — |
| 2010 | 86° | 47° | 66° | — | — |
| 2009 | 89° | 55° | 72° | — | — |
| 2008 | 85° | 57° | 71° | 0.03" | — |
| 2007 | 86° | 59° | 73° | 0.66" | — |
| 2006 | 77° | 50° | 64° | — | — |
| 2005 | 83° | 45° | 64° | — | — |
| 2004 | 89° | 49° | 69° | — | — |
| 2003 | 73° | 51° | 62° | — | — |
| 2002 | 89° | 53° | 71° | — | — |
| 2001 | 84° | 44° | 64° | — | — |
| 2000 | 75° | 49° | 62° | — | — |
| 1999 | 92° | 50° | 71° | 1.32" | — |
| 1998 | 85° | 55° | 70° | 0.3" | — |
| 1997 | 90° | 53° | 71° | — | — |
| 1996 | 89° | 45° | 67° | — | — |
| 1995 | 90° | 53° | 71° | — | — |
| 1994 | 76° | 51° | 63° | 0.18" | — |
| 1993coldest | 77° | 43° | 60° | — | — |
| 1992 | — | 45° | — | — | — |
| 1991 | 85° | 50° | 67° | — | — |
| 1990 | 89° | 50° | 70° | 0.53" | — |
| 1989 | 96° | 55° | 76° | — | — |
| 1988 | 95° | 50° | 73° | — | — |
| 1987 | 82° | 55° | 69° | — | — |
| 1986 | 84° | 49° | 66° | — | — |
| 1985 | 78° | 60° | 69° | 0.2" | — |
| 1984 | 90° | 53° | 71° | 0.13" | — |
| 1983 | 90° | 56° | 73° | — | — |
| 1982 | 96° | 54° | 75° | — | — |
| 1981 | 75° | 47° | 61° | — | — |
| 1980 | 81° | 45° | 63° | — | — |
| 1979 | 92° | 50° | 71° | — | — |
| 1978 | 90° | 53° | 71° | — | — |
| 1977 | 72° | 50° | 61° | — | — |
| 1976 | 77° | 46° | 62° | 0.43" | — |
| 1975 | 95° | 50° | 73° | — | — |
| 1974 | 79° | 48° | 63° | — | — |
| 1973 | 80° | 46° | 63° | 0.28" | — |
| 1972 | 72° | 50° | 61° | 0.97" | — |
| 1971 | 86° | 54° | 70° | — | — |
55 years of data from LONGMONT 2 ESE