August is one of the warmer months of the year in Boise, with average highs near 32.1°C and lows around 16.4°C (mean 24.3°C). It is one of the drier months, averaging 9 mm of rainfall and 30% relative humidity across the period.
August is one of the warmer months of the year in Boise. Across 45 years of records, the warmest August in Boise was 2022 — when the month averaged 28°C — while the coldest was 1993 at 20.4°C. Typical August days reach 32.1°C with nights near 16.4°C. The long-term trend is warming, about 0.4°C per decade.
August is one of the drier months in Boise, averaging 9 mm of rainfall. The wettest August on record was 2023 with 39 mm, while the driest was 2016 at 0 mm.
Relative humidity in Boise during August averages 30%. The most humid August was 1983 at 43%, and the least humid were 2001 and 2012 at 23%.
August receives about 6.6 kWh/m²/day of solar energy in Boise. The sunniest Augusts were 1998 and 2006 at 7.1 kWh/m²/day, and the cloudiest was 1984 at 6.
Average wind speed in Boise during August is 2 m/s. The windiest Augusts were 2002, 2008 and 2015, among others at 2.3 m/s, while the calmest was 1983 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 23.6°C | 23.7°C | 24.2°C | 24.9°C | 25.2°C | +1.6°C |
| Avg High | 31.5°C | 31.7°C | 32.1°C | 32.7°C | 32.6°C | +1.1°C |
| Avg Low | 15.6°C | 15.7°C | 16.2°C | 17.1°C | 17.8°C | +2.2°C |
| Avg Rain | 10 mm | 7 mm | 9 mm | 5 mm | 15 mm | +6 mm |
August temperatures in Boise have risen by about 1.4°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 4.9°C (1992) to a record high of 42°C (2018).
Rainfall in August is one of the drier months, averaging 9 mm, with a wettest year of 39 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.3°C per decade while lows rose 0.5°C per decade, narrowing the gap between day and night.
One of the best times to visit Boise
August is one of the best times to visit Boise. Expect days averaging 32.1°C and nights around 16.4°C (mean 24.3°C) — warmer than Boise's yearly average — with low rainfall (9 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 | 32.6°C | 25.2°C | 17.8°C | 37.6°C | 11.1°C | 26 mm | 34% | 2.1 m/s | 6.3 |
| 2024 | 32.7°C | 24.9°C | 17.2°C | 41.2°C | 9.3°C | 3 mm | 26% | 1.9 m/s | 6.5 |
| 2023 🌧️ | 31.9°C | 24.9°C | 17.8°C | 39.4°C | 12.7°C | 39 mm | 42% | 1.8 m/s | 6.1 |
| 2022 🔥 | 35.5°C | 28.0°C | 20.5°C | 40.5°C | 13.6°C | 7 mm | 28% | 1.8 m/s | 6.5 |
| 2021 | 30.7°C | 23.3°C | 15.9°C | 39.7°C | 10.5°C | 13 mm | 34% | 2.1 m/s | 6.2 |
| 2020 | 32.4°C | 24.9°C | 17.4°C | 37.8°C | 12.0°C | 3 mm | 32% | 2.2 m/s | 6.5 |
| 2019 | 32.8°C | 25.2°C | 17.6°C | 38.0°C | 13.1°C | 4 mm | 31% | 2 m/s | 6.8 |
| 2018 | 32.1°C | 24.5°C | 16.8°C | 42.0°C | 9.0°C | 2 mm | 27% | 2.1 m/s | 6.4 |
| 2017 | 33.4°C | 25.9°C | 18.3°C | 38.8°C | 14.7°C | 6 mm | 30% | 1.9 m/s | 6.2 |
| 2016 | 32.2°C | 24.3°C | 16.5°C | 36.8°C | 10.6°C | 0 mm | 25% | 2.1 m/s | 6.9 |
| 2015 | 32.7°C | 25.1°C | 17.5°C | 39.7°C | 11.1°C | 5 mm | 28% | 2.3 m/s | 6.5 |
| 2014 | 31.1°C | 24.1°C | 17.0°C | 38.1°C | 10.2°C | 22 mm | 38% | 1.9 m/s | 6.2 |
| 2013 | 34.4°C | 26.1°C | 17.8°C | 37.9°C | 13.2°C | 5 mm | 26% | 1.9 m/s | 6.6 |
| 2012 | 34.4°C | 26.0°C | 17.7°C | 39.7°C | 12.5°C | 1 mm | 23% | 1.9 m/s | 6.5 |
| 2011 | 33.4°C | 25.4°C | 17.5°C | 38.2°C | 13.4°C | 1 mm | 28% | 1.9 m/s | 6.9 |
| 2010 | 30.3°C | 22.5°C | 14.6°C | 39.1°C | 7.0°C | 8 mm | 32% | 2.1 m/s | 6.7 |
| 2009 | 30.6°C | 23.2°C | 15.7°C | 38.5°C | 8.6°C | 30 mm | 37% | 1.9 m/s | 6.4 |
| 2008 | 32.0°C | 24.0°C | 15.9°C | 38.3°C | 9.3°C | 4 mm | 27% | 2.3 m/s | 7 |
| 2007 | 32.3°C | 24.2°C | 16.0°C | 38.4°C | 11.6°C | 5 mm | 24% | 2.1 m/s | 6.8 |
| 2006 | 31.3°C | 23.2°C | 15.2°C | 38.0°C | 8.0°C | 1 mm | 27% | 2.1 m/s | 7.1 |
| 2005 | 32.6°C | 24.8°C | 17.0°C | 38.9°C | 10.3°C | 1 mm | 25% | 2.1 m/s | 7 |
| 2004 | 30.9°C | 23.5°C | 16.1°C | 38.5°C | 8.7°C | 26 mm | 37% | 1.8 m/s | 6.4 |
| 2003 | 33.2°C | 25.5°C | 17.7°C | 39.0°C | 13.8°C | 16 mm | 29% | 1.9 m/s | 6.5 |
| 2002 | 30.0°C | 22.0°C | 14.0°C | 36.6°C | 10.1°C | 3 mm | 28% | 2.3 m/s | 7 |
| 2001 | 35.0°C | 26.6°C | 18.1°C | 39.3°C | 12.6°C | 1 mm | 23% | 2.1 m/s | 6.9 |
| 2000 | 33.3°C | 24.8°C | 16.3°C | 40.2°C | 11.1°C | 3 mm | 25% | 2.3 m/s | 7 |
| 1999 | 32.5°C | 24.6°C | 16.8°C | 38.3°C | 6.9°C | 7 mm | 31% | 2 m/s | 6.2 |
| 1998 | 33.0°C | 24.5°C | 16.1°C | 39.1°C | 11.7°C | 5 mm | 32% | 2.1 m/s | 7.1 |
| 1997 | 31.8°C | 24.0°C | 16.1°C | 38.7°C | 12.4°C | 13 mm | 35% | 2 m/s | 6.8 |
| 1996 | 31.9°C | 23.8°C | 15.7°C | 38.5°C | 7.7°C | 4 mm | 30% | 2.1 m/s | 7 |
| 1995 | 30.6°C | 22.2°C | 13.9°C | 36.1°C | 7.1°C | 4 mm | 33% | 2 m/s | 6.6 |
| 1994 | 33.9°C | 25.4°C | 16.9°C | 39.8°C | 12.4°C | 1 mm | 24% | 2 m/s | 6.8 |
| 1993 ❄️ | 28.0°C | 20.4°C | 12.8°C | 35.0°C | 5.1°C | 16 mm | 40% | 2.1 m/s | 6.4 |
| 1992 | 31.8°C | 23.7°C | 15.6°C | 39.0°C | 4.9°C | 2 mm | 25% | 2.1 m/s | 6.9 |
| 1991 | 32.7°C | 24.9°C | 17.1°C | 38.2°C | 12.8°C | 2 mm | 27% | 1.8 m/s | 6.7 |
| 1990 | 31.1°C | 23.6°C | 16.1°C | 41.8°C | 9.5°C | 18 mm | 35% | 1.8 m/s | 6.5 |
| 1989 | 29.1°C | 21.6°C | 14.1°C | 36.8°C | 7.5°C | 15 mm | 35% | 2.1 m/s | 6.4 |
| 1988 | 31.7°C | 23.2°C | 14.7°C | 38.2°C | 9.8°C | 2 mm | 23% | 2.1 m/s | 6.8 |
| 1987 | 30.2°C | 22.1°C | 14.0°C | 38.0°C | 8.8°C | 5 mm | 28% | 2.2 m/s | 6.9 |
| 1986 | 33.6°C | 25.6°C | 17.7°C | 39.1°C | 11.1°C | 4 mm | 27% | 1.8 m/s | 6.7 |
| 1985 | 29.2°C | 21.1°C | 13.1°C | 36.1°C | 7.7°C | 1 mm | 30% | 2.3 m/s | 6.8 |
| 1984 | 32.6°C | 24.6°C | 16.5°C | 36.9°C | 10.5°C | 19 mm | 35% | 2.1 m/s | 6 |
| 1983 | 31.5°C | 24.2°C | 16.9°C | 41.7°C | 11.4°C | 32 mm | 43% | 1.6 m/s | — |
| 1982 | 31.8°C | 24.1°C | 16.5°C | 38.1°C | 11.2°C | 5 mm | 35% | 1.8 m/s | — |
| 1981 | 33.9°C | 25.5°C | 17.1°C | 38.3°C | 9.6°C | 2 mm | 25% | 1.9 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 32.1°C with lows near 16.4°C (mean 24.3°C), based on 45 years of NASA POWER data.
August averages 9 mm of rainfall in Boise, one of the drier months. The wettest on record was 39 mm in 2023.
The hottest August reached 42°C in 2018. The coldest dipped to 4.9°C in 1992.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.4°C. Daytime highs moved from 31.8°C to 32.7°C and overnight lows from 16°C to 17.8°C over the same span.
August is one of the warmer months of the year in Boise and one of the drier months, so plan for around 32.1°C daytime highs and 16.4°C at night.
Not quite — August is the 11th coolest month in Boise, averaging 24.3°C.
For August in Boise, pack light, breathable clothing and sun protection, with typical highs of 32.1°C and lows of 16.4°C.
Relative humidity in August averages 30% — relatively dry.
Average wind speed in August is 2 m/s. The windiest August on record averaged 2.3 m/s (1985).
The wettest August on record was 2023 with 39 mm. On average, August sees 9 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 Boise 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.
