Weather on September 12
Longmont, CO
55 Years of Data
Avg High
78°F
Avg Low
48°F
Warmest
2021
76°F avg
Coldest
1989
37°F avg
About This Date
September 12th in Longmont, CO typically brings pleasant fall weather, with average highs around 78°F and lows near 48°F — a 30°F daily swing. Over 55 years of records, the warmest September 12th was in 2021 (76°F average), while the coldest was 1989 (37°F) — a 39°F range across recorded history. Precipitation has occurred on 36% of recorded September 12th dates, with snow falling 2% of the time. The last decade has been 1.8°F warmer on this date compared to 20-30 years ago.
The last decade has been 1.8°F warmer on this date compared to 20-30 years ago.
Planning for September 12th in Longmont, CO? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Warming Trend
1.0°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 90° | 57° | 73° | — | — |
| 2024 | 85° | 50° | 67° | — | — |
| 2023 | 70° | 48° | 59° | 0.08" | — |
| 2022 | 78° | 44° | 61° | — | — |
| 2021warmest | 95° | 58° | 76° | 0.08" | — |
| 2020 | 68° | 40° | 54° | — | — |
| 2019 | 79° | 50° | 64° | 0.43" | — |
| 2018 | 90° | 52° | 71° | — | — |
| 2017 | 86° | 54° | 70° | — | — |
| 2016 | 83° | 57° | 70° | — | — |
| 2015 | 85° | 46° | 65° | — | — |
| 2014 | 44° | 32° | 38° | 1.6" | 0.5" |
| 2013 | 67° | 57° | 62° | 23.06" | — |
| 2012 | 77° | 51° | 64° | 3.53" | — |
| 2011 | 80° | 55° | 68° | — | — |
| 2010 | 85° | 51° | 68° | — | — |
| 2009 | 69° | 48° | 59° | 0.13" | — |
| 2008 | 63° | 47° | 55° | 3.15" | — |
| 2007 | 87° | 49° | 68° | — | — |
| 2006 | 76° | 44° | 60° | 0.41" | — |
| 2005 | 85° | 59° | 72° | — | — |
| 2004 | 86° | 48° | 67° | — | — |
| 2003 | 71° | 41° | 56° | — | — |
| 2002 | 74° | 45° | 59° | 0.46" | — |
| 2001 | 89° | 40° | 64° | — | — |
| 2000 | 82° | 39° | 61° | — | — |
| 1999 | 81° | 41° | 61° | — | — |
| 1998 | 94° | 57° | 75° | — | — |
| 1997 | 88° | 52° | 70° | — | — |
| 1996 | 76° | 49° | 62° | 1.68" | — |
| 1995 | 82° | 41° | 62° | — | — |
| 1994 | 91° | 50° | 71° | — | — |
| 1993 | 93° | 47° | 70° | — | — |
| 1992 | 94° | — | — | — | — |
| 1991 | 81° | 50° | 65° | 0.25" | — |
| 1990 | 87° | 47° | 67° | — | — |
| 1989coldest | 42° | 32° | 37° | 0.33" | — |
| 1988 | 75° | 38° | 56° | 2.26" | — |
| 1987 | 85° | 45° | 65° | — | — |
| 1986 | 76° | 41° | 58° | — | — |
| 1985 | 76° | 46° | 61° | — | — |
| 1984 | 73° | 53° | 63° | — | — |
| 1983 | 93° | 47° | 70° | — | — |
| 1982 | 60° | 43° | 51° | 1.47" | — |
| 1981 | 83° | 50° | 66° | — | — |
| 1980 | 83° | 52° | 67° | — | — |
| 1979 | 63° | 49° | 56° | 0.1" | — |
| 1978 | 76° | 47° | 61° | — | — |
| 1977 | 77° | 53° | 65° | — | — |
| 1976 | 86° | 52° | 69° | — | — |
| 1975 | 49° | 43° | 46° | 0.23" | — |
| 1974 | 58° | 33° | 45° | 1.57" | — |
| 1973 | 68° | 49° | 58° | 0.23" | — |
| 1972 | 73° | 50° | 62° | 0.08" | — |
| 1971 | 87° | 55° | 71° | — | — |
55 years of data from LONGMONT 2 ESE