Boise, ID weather in August
Expect hot, dry weather in Boise in August, with highs near 91°F and lows near 61°F. Rain falls on about 2 days. It is one of the warmest months in Boise.
- Normal high
- 91°F
- Normal low
- 61°F
- Wet days
- 2
- 0.2 in total
- Muggy days
- 0
- dew point 65°F+
How August changes from start to finish
| August 1 | August 31 | |
|---|---|---|
| Normal high | 95°F | 86°F |
| Normal low | 64°F | 57°F |
| Chance of a wet day | 7% | 9% |
| Sunrise / sunset | 6:34 am / 9:08 pm | 7:07 am / 8:22 pm |
| Daylight | 14.6 h | 13.3 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Mountain Time).
A typical August day
- 6 am62°Fdew point 42°F
- 9 am72°Fdew point 43°F
- Noon83°Fdew point 43°F
- 3 pm88°Fdew point 40°F
- 6 pm88°Fdew point 39°F
- 9 pm77°Fdew point 42°F
NOAA hourly normals (local standard time) from Boise Air Terminal (4 mi away); average wind 7 mph; clear or few clouds in 92% of daytime hours, mostly cloudy or overcast in 6%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F3 of 31
- Hot dayshigh 90°F or more20 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow2 of 31
- Notable rainat least 0.10 in0 of 31
- Freezing nightslow 32°F or below0 of 31
- Snow on the groundsnow depth 1 in or more0 of 31
Average days per August, counted from daily records for each year 1991-2020.
Rain in August
Normal precipitation is 0.2 in; a dry August brings about 0.0 in and a wet one about 0.2 in (25th and 75th percentiles). Days with half an inch or more are rare.
How August varies from year to year
- Warmest August, 1991-20202001: average high 95°F
- Coolest August1993: average high 84°F
- Wettest August2009: 1.8 in
- Driest August1992: no measurable precipitation
- Highest reading110°F (August 10, 2018)
- Lowest reading34°F (August 25, 1992)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
August compared with July and September
| July | August | September | |
|---|---|---|---|
| Normal high | 93°F | 91°F | 80°F |
| Normal low | 62°F | 61°F | 53°F |
| Wet days | 2 | 2 | 4 |
| Comfortable days | 2 | 3 | 13 |
| Daylight | 15.1 h | 13.9 h | 12.5 h |
Highs change by -2°F from July and -11°F into September.
Nearby alternatives in August
- Cooler: Sun Valley, ID93 mi · high 79°F · 4 wet days
How Boise ranks in August
- Normal high119th warmest of 378 cities; 1st of 2 in Idaho
- Wet days62nd driest of 378
- Comfortable days158th most of 341
What to pack for Boise in August
- Light, breathable clothing – highs near 91°F
- Layers – afternoons near 91°F but nights near 61°F
Heating and cooling
August has 8 heating degree days and 341 cooling degree days (base 65°F), 5% of the year's total heating and cooling demand.
Questions
How hot is Boise in August?
The normal high is 91°F and the normal low is 61°F. From 1991 to 2020 the hottest August reading was 110°F (August 10, 2018).
Does it rain a lot in Boise in August?
About 2 days in August have at least 0.01 in of precipitation, and the normal total is 0.2 in. The wettest August in 1991-2020 was in 2009 (1.8 in); the driest was in 1992, with no measurable precipitation.
Is August a good time to visit Boise?
August ranks 8th of 12 months on our comfort score for Boise (48 out of 100). It has about 3 comfortable days and about 20 days at 90°F or hotter. The best month is May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth, frost dates, humidity and wind by hour and cloud cover: Boise Air Terminal (USW00024131), 3.7 mi SSW of the city center, 2,814 ft (114 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Boise Air Terminal/Gowen Fd Airport (726810-24131), 3.7 mi SSW of the city center, 2,823 ft (123 ft higher than the city). Hourly observations, 1991-2020.