Boise weather in September
Temperature, rain and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Excellent
Best time to visit: May – June, September – October
What is the weather like in Boise in September?
In September, Boise is warm: daytime highs average 26 °C, and nights cool down to about 13 °C. With around 9 hours of sunshine a day, there is plenty of sun. Rain is rare: about 2 days bring 11 mm in total. On about 8 days the thermometer climbs to 30 °C or more. All in all, September is an excellent month for a holiday in Boise.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 68 | 100 | 92 |
| Day | 32° | 26° | 18° |
| Night | 18° | 13° | 6° |
| Sun | 11 h | 9 h | 7 h |
| Rain days | 1 | 2 | 4 |
More details for September
- Daylight
- 12 h 35 min07:23 – 19:58
- UV index
- 6 · highclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 14 km/haverage daily peakAll months
- Cloud cover
- 28 %on averageAll months
- Hot days
- 8 days30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC−6America/Boise
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %100 %
- Few rainy daysweight 30 %100 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- A jumper for the evenings
Boise in September: quick answers
Is Boise hot in September?
Warm rather than hot: in September, daytime highs in Boise average 26 °C and nights cool to about 13 °C. On about 8 days the thermometer climbs to 30 °C or more.
Does it rain much in Boise in September?
Rain is rare: about 2 days bring 11 mm in total.
Boise month by month
The whole year in BoiseAll destinations: USAWhere to go in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences