August is one of the warmer months of the year in Great Falls, with average highs near 27.5°C and lows around 12.6°C (mean 20.1°C). It is about average for rainfall, averaging 39 mm of rainfall and 50% relative humidity across the period.
August is one of the warmer months of the year in Great Falls. Across 45 years of records, the warmest August in Great Falls was 2022 — when the month averaged 23°C — while the coldest was 1993 at 16.1°C. Typical August days reach 27.5°C with nights near 12.6°C. The long-term trend is warming, about 0.2°C per decade.
August is about average for rainfall in Great Falls, averaging 39 mm of rainfall. The wettest August on record was 1985 with 109 mm, while the driest was 2000 at 6 mm.
Relative humidity in Great Falls during August averages 50%. The most humid August was 1993 at 63%, and the least humid was 2001 at 37%.
August receives about 5.9 kWh/m²/day of solar energy in Great Falls. The sunniest August was 2001 at 6.6 kWh/m²/day, and the cloudiest was 2021 at 5.
Average wind speed in Great Falls during August is 2 m/s. The windiest August was 2008 at 2.4 m/s, while the calmest was 1981 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 19.6°C | 19.8°C | 20.1°C | 20.2°C | 20.9°C | +1.3°C |
| Avg High | 27.1°C | 27.3°C | 27.9°C | 27.5°C | 27.9°C | +0.8°C |
| Avg Low | 12.0°C | 12.4°C | 12.3°C | 12.8°C | 13.8°C | +1.8°C |
| Avg Rain | 46 mm | 41 mm | 31 mm | 38 mm | 42 mm | -5 mm |
August temperatures in Great Falls have risen by about 0.5°C between 1981–1985 and 2021–2025.
August has ranged from a record low of -0.4°C (1992) to a record high of 38.2°C (1983).
Rainfall in August is about average for rainfall, averaging 39 mm, with a wettest year of 109 mm.
One of the best times to visit Great Falls
August is one of the best times to visit Great Falls. Expect days averaging 27.5°C and nights around 12.6°C (mean 20.1°C) — warmer than Great Falls's yearly average — with moderate rainfall (39 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 | 27.4°C | 20.7°C | 14.0°C | 34.9°C | 8.5°C | 43 mm | 57% | 1.9 m/s | 5.7 |
| 2024 | 27.6°C | 20.4°C | 13.3°C | 34.5°C | 8.5°C | 50 mm | 55% | 1.8 m/s | 5.6 |
| 2023 | 27.7°C | 21.0°C | 14.2°C | 35.6°C | 9.2°C | 41 mm | 54% | 2.2 m/s | 5.7 |
| 2022 🔥 | 30.4°C | 23.0°C | 15.7°C | 37.2°C | 10.2°C | 38 mm | 46% | 2.1 m/s | 6.4 |
| 2021 | 26.0°C | 19.1°C | 12.2°C | 33.8°C | 2.6°C | 65 mm | 54% | 2.3 m/s | 5 |
| 2020 | 28.5°C | 21.0°C | 13.6°C | 34.8°C | 8.3°C | 12 mm | 47% | 2 m/s | 5.9 |
| 2019 | 27.1°C | 20.1°C | 13.0°C | 34.6°C | 7.4°C | 44 mm | 55% | 2 m/s | 5.7 |
| 2018 | 27.2°C | 19.8°C | 12.4°C | 37.2°C | 4.3°C | 24 mm | 49% | 2.2 m/s | 5.5 |
| 2017 | 28.0°C | 20.5°C | 13.0°C | 33.3°C | 10.3°C | 8 mm | 45% | 1.8 m/s | 5.8 |
| 2016 | 26.8°C | 19.4°C | 12.0°C | 34.0°C | 7.2°C | 39 mm | 50% | 2.1 m/s | 6 |
| 2015 | 28.3°C | 20.6°C | 12.9°C | 36.4°C | 5.9°C | 17 mm | 46% | 2.2 m/s | 5.6 |
| 2014 | 26.3°C | 19.9°C | 13.5°C | 36.5°C | 6.8°C | 91 mm | 57% | 1.9 m/s | 5.3 |
| 2013 | 29.0°C | 21.5°C | 14.0°C | 34.4°C | 9.6°C | 42 mm | 52% | 1.9 m/s | 6 |
| 2012 | 29.3°C | 21.0°C | 12.7°C | 37.2°C | 6.5°C | 23 mm | 44% | 1.9 m/s | 6.4 |
| 2011 | 28.3°C | 20.8°C | 13.3°C | 33.2°C | 8.9°C | 18 mm | 49% | 1.9 m/s | 6.3 |
| 2010 | 25.1°C | 18.1°C | 11.2°C | 34.3°C | 4.4°C | 71 mm | 56% | 2.2 m/s | 5.8 |
| 2009 | 25.8°C | 18.7°C | 11.6°C | 33.4°C | 5.9°C | 43 mm | 56% | 2 m/s | 5.8 |
| 2008 | 27.9°C | 20.2°C | 12.4°C | 35.3°C | 5.7°C | 33 mm | 45% | 2.4 m/s | 6 |
| 2007 | 28.6°C | 20.5°C | 12.5°C | 35.1°C | 7.0°C | 10 mm | 43% | 2.2 m/s | 6.1 |
| 2006 | 27.6°C | 19.8°C | 12.1°C | 35.5°C | 7.0°C | 33 mm | 45% | 1.8 m/s | 6.1 |
| 2005 | 27.0°C | 19.2°C | 11.3°C | 35.3°C | 4.7°C | 32 mm | 47% | 2.2 m/s | 6 |
| 2004 | 25.9°C | 18.7°C | 11.6°C | 32.7°C | 5.6°C | 68 mm | 55% | 2.1 m/s | 5.7 |
| 2003 | 31.0°C | 22.9°C | 14.8°C | 37.9°C | 7.4°C | 28 mm | 42% | 1.8 m/s | 6.1 |
| 2002 | 24.5°C | 17.2°C | 9.9°C | 29.2°C | 5.2°C | 54 mm | 56% | 2.2 m/s | 5.5 |
| 2001 | 30.8°C | 22.2°C | 13.7°C | 37.1°C | 8.7°C | 8 mm | 37% | 1.8 m/s | 6.6 |
| 2000 | 29.4°C | 21.2°C | 13.0°C | 36.7°C | 7.1°C | 6 mm | 38% | 2 m/s | 6.2 |
| 1999 | 28.0°C | 20.8°C | 13.5°C | 34.0°C | 6.0°C | 68 mm | 51% | 2.1 m/s | 5.7 |
| 1998 | 29.3°C | 21.6°C | 13.9°C | 34.7°C | 9.7°C | 36 mm | 48% | 1.9 m/s | 6.2 |
| 1997 | 26.6°C | 19.3°C | 12.1°C | 32.6°C | 6.0°C | 57 mm | 57% | 1.9 m/s | 5.9 |
| 1996 | 28.2°C | 20.3°C | 12.3°C | 34.2°C | 7.7°C | 17 mm | 44% | 2.2 m/s | 6.2 |
| 1995 | 26.6°C | 18.7°C | 10.8°C | 33.1°C | 6.4°C | 31 mm | 51% | 2.2 m/s | 6.1 |
| 1994 | 28.6°C | 21.0°C | 13.3°C | 35.0°C | 7.4°C | 14 mm | 46% | 1.9 m/s | 5.5 |
| 1993 ❄️ | 22.6°C | 16.1°C | 9.5°C | 31.2°C | 2.8°C | 82 mm | 63% | 2 m/s | 5.5 |
| 1992 | 25.3°C | 18.0°C | 10.7°C | 33.2°C | -0.4°C | 33 mm | 47% | 2.1 m/s | 5.9 |
| 1991 | 30.1°C | 22.3°C | 14.4°C | 35.7°C | 9.8°C | 19 mm | 45% | 1.9 m/s | 6.3 |
| 1990 | 27.5°C | 20.3°C | 13.2°C | 36.2°C | 7.3°C | 56 mm | 53% | 2 m/s | 5.9 |
| 1989 | 24.4°C | 17.9°C | 11.4°C | 31.5°C | 5.1°C | 94 mm | 58% | 1.9 m/s | 5.6 |
| 1988 | 28.4°C | 20.0°C | 11.6°C | 34.4°C | 8.0°C | 6 mm | 37% | 2.1 m/s | 6 |
| 1987 | 23.7°C | 16.5°C | 9.2°C | 32.6°C | 5.6°C | 47 mm | 52% | 2.2 m/s | 5.9 |
| 1986 | 27.7°C | 20.1°C | 12.5°C | 33.5°C | 7.9°C | 40 mm | 48% | 2 m/s | 5.8 |
| 1985 🌧️ | 23.7°C | 16.6°C | 9.4°C | 33.8°C | 3.7°C | 109 mm | 55% | 2.1 m/s | 5.3 |
| 1984 | 29.4°C | 21.3°C | 13.3°C | 36.6°C | 6.8°C | 41 mm | 44% | 2.2 m/s | 5.5 |
| 1983 | 30.3°C | 22.7°C | 15.0°C | 38.2°C | 10.4°C | 16 mm | 49% | 1.9 m/s | — |
| 1982 | 27.7°C | 20.1°C | 12.5°C | 33.9°C | 6.9°C | 22 mm | 50% | 2 m/s | — |
| 1981 | 28.9°C | 21.0°C | 13.2°C | 33.9°C | 6.3°C | 42 mm | 49% | 1.6 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 27.5°C with lows near 12.6°C (mean 20.1°C), based on 45 years of NASA POWER data.
August averages 39 mm of rainfall in Great Falls, about average for rainfall. The wettest on record was 109 mm in 1985.
The hottest August reached 38.2°C in 1983. The coldest dipped to -0.4°C in 1992.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 0.5°C — but days and nights have moved in opposite directions. Overnight lows rose from 12.7°C to 13.9°C while daytime highs eased from 28°C to 27.8°C, narrowing the gap between day and night.
August is one of the warmer months of the year in Great Falls and about average for rainfall, so plan for around 27.5°C daytime highs and 12.6°C at night.
Not quite — August is the 11th coolest month in Great Falls, averaging 20.1°C.
For August in Great Falls, pack light layers you can adjust through the day, with typical highs of 27.5°C and lows of 12.6°C.
Relative humidity in August averages 50% — relatively dry.
Average wind speed in August is 2 m/s. The windiest August on record averaged 2.4 m/s (2008).
The wettest August on record was 1985 with 109 mm. On average, August sees 39 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 Great Falls 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.
