Weather on August 18
Boulder, CO
55 Years of Data
Avg High
86°F
Avg Low
57°F
Warmest
2020
80°F avg
Coldest
2009
62°F avg
About This Date
August 18th in Boulder, CO typically brings warm summer weather, with average highs around 86°F and lows near 57°F — a 29°F daily swing. Over 55 years of records, the warmest August 18th was in 2020 (80°F average), while the coldest was 2009 (62°F) — a 18°F range across recorded history. Rain or other precipitation has occurred on about 33% of August 18th dates historically, with the wettest August 18th recording 3.35" of rain. The last decade has been 5.3°F warmer on this date compared to 20-30 years ago.
The last decade has been 5.3°F warmer on this date compared to 20-30 years ago.
Planning for August 18th in Boulder, CO? Stay hydrated and seek shade during peak afternoon hours. Consider bringing rain gear or an umbrella.
Warming Trend
0.5°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 93° | 63° | 78° | — | — |
| 2024 | 95° | 64° | 80° | — | — |
| 2023 | 95° | 63° | 79° | — | — |
| 2022 | 88° | 57° | 72° | — | — |
| 2021 | 91° | 61° | 76° | — | — |
| 2020warmest | 95° | 64° | 80° | — | — |
| 2019 | 88° | 59° | 73° | — | — |
| 2018 | 81° | 54° | 67° | — | — |
| 2017 | 87° | 51° | 69° | — | — |
| 2016 | 86° | 65° | 75° | 0.03" | — |
| 2015 | 75° | 52° | 63° | — | — |
| 2014 | 88° | 57° | 72° | — | — |
| 2013 | 91° | 56° | 73° | — | — |
| 2012 | 81° | 54° | 67° | — | — |
| 2011 | 97° | 60° | 78° | — | — |
| 2010 | 95° | 60° | 78° | — | — |
| 2009coldest | 76° | 49° | 62° | — | — |
| 2008 | 77° | 49° | 63° | — | — |
| 2007 | 88° | 59° | 73° | — | — |
| 2006 | 84° | 61° | 72° | 0.2" | — |
| 2005 | 86° | 56° | 71° | 0.08" | — |
| 2004 | 77° | 54° | 65° | 1.83" | — |
| 2003 | 79° | 57° | 68° | 3.35" | — |
| 2002 | 98° | 54° | 76° | — | — |
| 2001 | 88° | 53° | 70° | — | — |
| 2000 | 73° | 60° | 67° | 0.41" | — |
| 1999 | 82° | 51° | 67° | — | — |
| 1998 | 88° | 60° | 74° | 0.03" | — |
| 1997 | 79° | 55° | 67° | 1.07" | — |
| 1996 | 86° | 55° | 71° | — | — |
| 1995 | 93° | 62° | 78° | — | — |
| 1994 | 87° | 57° | 72° | — | — |
| 1993 | 91° | 54° | 72° | 0.41" | — |
| 1992 | 78° | 49° | 63° | 0.03" | — |
| 1991 | 79° | 54° | 66° | 0.1" | — |
| 1990 | 78° | 51° | 65° | 0.03" | — |
| 1989 | 87° | 54° | 70° | — | — |
| 1988 | 85° | 52° | 68° | — | — |
| 1987 | 81° | 48° | 64° | — | — |
| 1986 | 97° | 59° | 78° | — | — |
| 1985 | 81° | 53° | 67° | — | — |
| 1984 | 77° | 59° | 68° | — | — |
| 1983 | 93° | 60° | 77° | 0.41" | — |
| 1982 | 91° | 60° | 76° | — | — |
| 1981 | 83° | 53° | 68° | — | — |
| 1980 | 90° | 56° | 73° | — | — |
| 1979 | 74° | 57° | 65° | 0.46" | — |
| 1978 | 89° | 55° | 72° | 0.28" | — |
| 1977 | 77° | 58° | 67° | 0.2" | — |
| 1976 | 85° | 56° | 70° | 0.18" | — |
| 1975 | 87° | 56° | 71° | — | — |
| 1974 | 91° | 58° | 74° | — | — |
| 1973 | 91° | 61° | 76° | — | — |
| 1972 | 88° | 56° | 72° | 0.03" | — |
| 1971 | 87° | 65° | 76° | — | — |
55 years of data from BOULDER MUNI AP