Boise weather in August: Boise, Idaho: normal highs, lows, rain and records for August
Boise in August has a normal high of 91°F and a normal low of 61°F, a daily mean of 76°F, falling from 95°F on the 1st to 86°F by the 31st. Measurable precipitation falls on 2 days in a normal August, 0.17 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 33°C and low of 16°C, 4 mm of precipitation in August.
- NOAA stationBoise Air Terminal
- Station IDUSW00024131
- Location43.57°N 116.24°W
- Elevation2,814 ft (858 m)
- From the center2 miles
- Population237,963
- Jan 39° 26°
- Feb 46° 29°
- Mar 56° 35°
- Apr 62° 40°
- May 72° 48°
- Jun 81° 54°
- Jul 93° 62°
- Aug 91° 61°
- Sep 80° 53°
- Oct 65° 42°
- Nov 49° 32°
- Dec 39° 25°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Boise in August?
The normal high is 91°F and the normal low 61°F, for a daily mean of 75.8°F. August is 1.5°F cooler than July and 9.5°F warmer than September. August is the 2nd warmest month of the year in Boise and the 12th wettest. Across the month the normal high falls 9°F, from 95°F on August 1 to 86°F on August 31. From one year to the next August's mean temperature typically moves about 2.2°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 74°F and 78°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 10%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 95°F | 64°F | 7% | 2% |
| August 8 | 93°F | 63°F | 7% | 2% |
| August 15 | 91°F | 61°F | 7% | 2% |
| August 22 | 89°F | 60°F | 8% | 2% |
| August 31 | 86°F | 57°F | 10% | 3% |
Every day of August: normal high, low and chance of precipitation (warmest afternoon August 1, coldest night August 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| August 1 | 95°F | 64°F | 7% | 2% | 14 h 40 min |
| August 2 | 94°F | 64°F | 7% | 2% | 14 h 30 min |
| August 3 | 94°F | 64°F | 7% | 2% | 14 h 30 min |
| August 4 | 94°F | 63°F | 7% | 2% | 14 h 30 min |
| August 5 | 94°F | 63°F | 7% | 2% | 14 h 30 min |
| August 6 | 94°F | 63°F | 7% | 2% | 14 h 20 min |
| August 7 | 93°F | 63°F | 7% | 2% | 14 h 20 min |
| August 8 | 93°F | 63°F | 7% | 2% | 14 h 20 min |
| August 9 | 93°F | 63°F | 7% | 2% | 14 h 20 min |
| August 10 | 93°F | 62°F | 7% | 2% | 14 h 10 min |
| August 11 | 92°F | 62°F | 7% | 2% | 14 h 10 min |
| August 12 | 92°F | 62°F | 7% | 2% | 14 h 10 min |
| August 13 | 92°F | 62°F | 7% | 2% | 14 h 10 min |
| August 14 | 92°F | 62°F | 7% | 2% | 14 h |
| August 15 | 91°F | 61°F | 7% | 2% | 14 h |
| August 16 | 91°F | 61°F | 7% | 2% | 14 h |
| August 17 | 91°F | 61°F | 7% | 2% | 14 h |
| August 18 | 90°F | 61°F | 8% | 2% | 13 h 50 min |
| August 19 | 90°F | 60°F | 8% | 2% | 13 h 50 min |
| August 20 | 90°F | 60°F | 8% | 2% | 13 h 50 min |
| August 21 | 89°F | 60°F | 8% | 2% | 13 h 50 min |
| August 22 | 89°F | 60°F | 8% | 2% | 13 h 40 min |
| August 23 | 89°F | 59°F | 8% | 2% | 13 h 40 min |
| August 24 | 88°F | 59°F | 8% | 2% | 13 h 40 min |
| August 25 | 88°F | 59°F | 9% | 2% | 13 h 40 min |
| August 26 | 88°F | 58°F | 9% | 2% | 13 h 30 min |
| August 27 | 87°F | 58°F | 9% | 2% | 13 h 30 min |
| August 28 | 87°F | 58°F | 9% | 2% | 13 h 30 min |
| August 29 | 87°F | 58°F | 9% | 3% | 13 h 20 min |
| August 30 | 86°F | 57°F | 10% | 3% | 13 h 20 min |
| August 31 | 86°F | 57°F | 10% | 3% | 13 h 20 min |
- Normal high
- 91°FAugust average
- Normal low
- 61°FAugust average
- Precipitation
- 0.17 inmonth total
- Days with precipitation
- 20.01 inch or more
- Days at 90°F or more
- 20
- Daylight
- 14 h 40 min to 13 h 20 minAugust 1 to August 31
- Days at 70°F or more
- 31
- Days at 80°F or more
- 29
- Sunshine
- 92%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024131; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Boise in August?
On a given August day the chance of 0.01 inch or more is 8% on average, highest around August 31 (10%). In all, 0.17 in falls on 2 days of a normal August.
In a normal August in Boise, 20 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024131.
How humid and windy is Boise in August?
At 3 p.m. the normal temperature is 84°F with 20% relative humidity and a dew point of 39°F; at 6 a.m. it is 59°F with 49% humidity. The wind averages 7.0 mph, most often from the northwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 59°F | 40°F | 49% | 5.6 mph | 92% |
| 9 a.m. | 69°F | 41°F | 36% | 6.1 mph | 93% |
| noon | 79°F | 41°F | 26% | 8.0 mph | 92% |
| 3 p.m. | 84°F | 39°F | 20% | 9.2 mph | 92% |
| 6 p.m. | 84°F | 38°F | 20% | 9.7 mph | 91% |
| 9 p.m. | 72°F | 40°F | 31% | 5.2 mph | 91% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024131. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for August in Boise?
The warmest August temperature on Boise's official record (since 1875) is 110°F, on August 4, 1961; the coldest is 32°F, on August 25, 1892. The wettest August brought 2.79 in (2023).
The August mean against the 1991-2020 normal of 75.8°F: 2021 74.4°F (−1.4), 2022 81.9°F (+6.1), 2023 77.9°F (+2.1), 2024 77.5°F (+1.7), 2025 76.7°F (+0.9), 2026 78.8°F (+3.0). 5 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 74.4°F | −1.4°F | 0.19 in |
| 2022 | 81.9°F | +6.1°F | 0.09 in |
| 2023 | 77.9°F | +2.1°F | 2.79 in |
| 2024 | 77.5°F | +1.7°F | 0.02 in |
| 2025 | 76.7°F | +0.9°F | 0.51 in |
| 2026 | 78.8°F | +3.0°F | 0.00 in |
Source: records: ACIS, NWS threaded record BOIthr; recent months: ACIS, station USW00024131. Records and recent months use complete months only.
How does August in Boise compare across Idaho?
Across the 85 places PlainClimate covers in Idaho, August normal highs run from 69°F in Mullan to 97°F in Glenns Ferry; Boise's is 91°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.