August is one of the warmer months of the year in Longmont, with average highs near 30.2°C and lows around 15.1°C (mean 22.7°C). It is about average for rainfall, averaging 47 mm of rainfall and 44% relative humidity across the period.
August is one of the warmer months of the year in Longmont. Across 45 years of records, the warmest August in Longmont was 2020 — when the month averaged 25.2°C — while the coldest was 2004 at 20.2°C. Typical August days reach 30.2°C with nights near 15.1°C. The long-term trend is warming, about 0.4°C per decade.
August is about average for rainfall in Longmont, averaging 47 mm of rainfall. The wettest August on record was 2008 with 92 mm, while the driest was 2012 at 13 mm.
Relative humidity in Longmont during August averages 44%. The most humid August was 1997 at 55%, and the least humid was 2020 at 31%.
August receives about 5.8 kWh/m²/day of solar energy in Longmont. The sunniest Augusts were 1985 and 1995 at 6.3 kWh/m²/day, and the cloudiest was 2013 at 5.2.
Average wind speed in Longmont during August is 2.1 m/s. The windiest Augusts were 2018, 2022 and 2023, among others at 2.3 m/s, while the calmest was 2014 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.1°C | 21.9°C | 22.6°C | 22.9°C | 24.1°C | +2°C |
| Avg High | 29.5°C | 29.2°C | 30.2°C | 30.6°C | 32.0°C | +2.5°C |
| Avg Low | 14.8°C | 14.6°C | 15.0°C | 15.2°C | 16.1°C | +1.3°C |
| Avg Rain | 45 mm | 55 mm | 56 mm | 35 mm | 39 mm | -6 mm |
August temperatures in Longmont have risen by about 1.5°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 6.1°C (1992) to a record high of 39°C (2008).
Rainfall in August is about average for rainfall, averaging 47 mm, with a wettest year of 92 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.6°C per decade while lows rose 0.3°C per decade, widening the gap between day and night.
One of the best times to visit Longmont
August is one of the best times to visit Longmont. Expect days averaging 30.2°C and nights around 15.1°C (mean 22.7°C) — warmer than Longmont's yearly average — with moderate rainfall (47 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 32.0°C | 23.9°C | 15.7°C | 38.3°C | 11.2°C | 42 mm | 39% | 2.2 m/s | 5.5 |
| 2024 | 32.4°C | 24.3°C | 16.3°C | 37.8°C | 12.4°C | 47 mm | 41% | 2.2 m/s | 5.8 |
| 2023 | 31.0°C | 23.2°C | 15.4°C | 37.8°C | 9.9°C | 56 mm | 44% | 2.3 m/s | 5.9 |
| 2022 | 31.2°C | 23.9°C | 16.6°C | 36.3°C | 12.6°C | 48 mm | 44% | 2.3 m/s | 5.9 |
| 2021 | 32.1°C | 23.9°C | 15.6°C | 36.3°C | 10.1°C | 21 mm | 37% | 2.1 m/s | 6 |
| 2020 🔥 | 33.5°C | 25.2°C | 17.0°C | 37.0°C | 8.9°C | 18 mm | 31% | 2.2 m/s | 5.9 |
| 2019 | 32.4°C | 24.3°C | 16.2°C | 36.0°C | 12.1°C | 27 mm | 40% | 2.1 m/s | 6 |
| 2018 | 30.2°C | 22.4°C | 14.7°C | 34.6°C | 9.5°C | 23 mm | 41% | 2.3 m/s | 5.9 |
| 2017 | 29.2°C | 21.7°C | 14.1°C | 34.4°C | 11.3°C | 53 mm | 46% | 2.1 m/s | 5.4 |
| 2016 | 29.4°C | 21.8°C | 14.2°C | 35.3°C | 7.1°C | 29 mm | 44% | 2.3 m/s | 5.6 |
| 2015 | 30.9°C | 23.2°C | 15.4°C | 36.0°C | 6.7°C | 32 mm | 43% | 2.1 m/s | 5.9 |
| 2014 | 28.2°C | 21.0°C | 13.9°C | 33.1°C | 9.8°C | 52 mm | 50% | 1.6 m/s | 5.6 |
| 2013 | 30.4°C | 23.1°C | 15.9°C | 35.8°C | 11.9°C | 59 mm | 46% | 2.1 m/s | 5.2 |
| 2012 | 31.9°C | 23.9°C | 15.8°C | 35.6°C | 10.4°C | 13 mm | 34% | 2.3 m/s | 5.7 |
| 2011 | 32.6°C | 24.7°C | 16.8°C | 35.9°C | 13.2°C | 19 mm | 39% | 2 m/s | 6.1 |
| 2010 | 30.4°C | 22.8°C | 15.2°C | 34.8°C | 11.1°C | 43 mm | 44% | 2.1 m/s | 6 |
| 2009 | 29.8°C | 21.7°C | 13.5°C | 34.9°C | 8.9°C | 29 mm | 44% | 1.9 m/s | 6.2 |
| 2008 🌧️ | 29.5°C | 22.1°C | 14.6°C | 39.0°C | 7.9°C | 92 mm | 47% | 2 m/s | 5.8 |
| 2007 | 31.5°C | 24.0°C | 16.4°C | 36.5°C | 11.6°C | 74 mm | 47% | 2.1 m/s | 5.7 |
| 2006 | 29.4°C | 22.4°C | 15.4°C | 34.5°C | 9.9°C | 48 mm | 47% | 2.3 m/s | 5.5 |
| 2005 | 29.4°C | 21.9°C | 14.4°C | 35.9°C | 9.3°C | 52 mm | 45% | 2 m/s | 5.7 |
| 2004 ❄️ | 27.8°C | 20.2°C | 12.6°C | 34.9°C | 8.0°C | 64 mm | 48% | 2 m/s | 5.8 |
| 2003 | 31.3°C | 24.0°C | 16.6°C | 36.2°C | 9.5°C | 63 mm | 43% | 2.2 m/s | 5.7 |
| 2002 | 31.2°C | 22.8°C | 14.3°C | 38.0°C | 9.2°C | 29 mm | 36% | 2.2 m/s | 6 |
| 2001 | 30.2°C | 23.1°C | 16.0°C | 35.1°C | 12.3°C | 51 mm | 43% | 2.2 m/s | 5.5 |
| 2000 | 31.7°C | 24.1°C | 16.6°C | 36.3°C | 12.0°C | 60 mm | 41% | 2.1 m/s | 5.4 |
| 1999 | 28.6°C | 21.6°C | 14.6°C | 32.5°C | 10.4°C | 72 mm | 51% | 2.1 m/s | 5.7 |
| 1998 | 29.5°C | 22.2°C | 14.9°C | 33.8°C | 11.7°C | 42 mm | 47% | 2 m/s | 6.1 |
| 1997 | 27.9°C | 21.0°C | 14.0°C | 32.2°C | 9.5°C | 90 mm | 55% | 2 m/s | 5.7 |
| 1996 | 30.2°C | 22.3°C | 14.5°C | 35.9°C | 11.4°C | 30 mm | 42% | 2.1 m/s | 6.1 |
| 1995 | 31.8°C | 24.2°C | 16.5°C | 36.7°C | 10.2°C | 30 mm | 41% | 2 m/s | 6.3 |
| 1994 | 30.7°C | 23.3°C | 15.9°C | 36.1°C | 11.7°C | 53 mm | 43% | 2.1 m/s | 5.5 |
| 1993 | 27.7°C | 20.7°C | 13.7°C | 33.3°C | 7.0°C | 37 mm | 47% | 2 m/s | 5.8 |
| 1992 | 27.7°C | 20.4°C | 13.1°C | 34.0°C | 6.1°C | 80 mm | 49% | 2 m/s | 5.4 |
| 1991 | 28.6°C | 21.7°C | 14.8°C | 32.2°C | 11.7°C | 63 mm | 49% | 2.1 m/s | 5.5 |
| 1990 | 29.2°C | 21.7°C | 14.1°C | 36.7°C | 10.8°C | 52 mm | 45% | 2.1 m/s | 5.9 |
| 1989 | 29.4°C | 21.6°C | 13.9°C | 33.1°C | 11.1°C | 40 mm | 43% | 2.1 m/s | 6 |
| 1988 | 30.7°C | 23.0°C | 15.3°C | 37.5°C | 10.7°C | 43 mm | 42% | 2.1 m/s | 5.8 |
| 1987 | 28.4°C | 21.0°C | 13.7°C | 34.7°C | 8.6°C | 54 mm | 47% | 2.1 m/s | 5.8 |
| 1986 | 29.7°C | 22.1°C | 14.5°C | 36.0°C | 10.8°C | 35 mm | 43% | 2.2 m/s | 5.4 |
| 1985 | 31.6°C | 22.9°C | 14.1°C | 36.2°C | 9.7°C | 16 mm | 33% | 2 m/s | 6.3 |
| 1984 | 28.6°C | 21.9°C | 15.2°C | 32.2°C | 11.5°C | 78 mm | 53% | 2 m/s | 5.5 |
| 1983 | 29.1°C | 22.8°C | 16.5°C | 34.3°C | 13.9°C | 48 mm | 53% | 1.9 m/s | — |
| 1982 | 29.7°C | 22.8°C | 15.9°C | 33.2°C | 13.3°C | 53 mm | 50% | 2 m/s | — |
| 1981 | 28.2°C | 21.1°C | 14.0°C | 34.6°C | 10.6°C | 41 mm | 49% | 2 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 30.2°C with lows near 15.1°C (mean 22.7°C), based on 45 years of NASA POWER data.
August averages 47 mm of rainfall in Longmont, about average for rainfall. The wettest on record was 92 mm in 2008.
The hottest August reached 39°C in 2008. The coldest dipped to 6.1°C in 1992.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.5°C. Daytime highs moved from 29.4°C to 31.7°C and overnight lows from 15.1°C to 15.9°C over the same span.
August is one of the warmer months of the year in Longmont and about average for rainfall, so plan for around 30.2°C daytime highs and 15.1°C at night.
Not quite — August is the 11th coolest month in Longmont, averaging 22.7°C.
For August in Longmont, pack light, breathable clothing and sun protection, with typical highs of 30.2°C and lows of 15.1°C.
Relative humidity in August averages 44% — relatively dry.
Average wind speed in August is 2.1 m/s. The windiest August on record averaged 2.3 m/s (2006).
The wettest August on record was 2008 with 92 mm. On average, August sees 47 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Longmont behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
