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Boise Weather by Month
Average temperatures, rainfall and humidity for Boise, United States, month by month, built from OpenWeather’s historical records. Use it to see what a typical Boise month looks like before you travel — then check the live Boise forecast for the days ahead.
Warmest month
July
35°C average high
Coolest month
January
-4°C average low
Wettest month
May
44 mm of rain
Driest month
July
2 mm of rain
Average temperature and rainfall in Boise by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 4°C | -4°C | -25°C / 17°C | 19 mm | 81% | 10 km/h |
| February | 8°C | -2°C | -17°C / 17°C | 30 mm | 73% | 12 km/h |
| March | 14°C | 2°C | -9°C / 28°C | 29 mm | 61% | 13 km/h |
| April | 18°C | 4°C | -4°C / 31°C | 27 mm | 53% | 13 km/h |
| May | 23°C | 9°C | -1°C / 37°C | 44 mm | 51% | 13 km/h |
| June | 29°C | 13°C | 4°C / 42°C | 13 mm | 44% | 11 km/h |
| July | 35°C | 17°C | 6°C / 42°C | 2 mm | 35% | 11 km/h |
| August | 33°C | 16°C | 8°C / 42°C | 5 mm | 38% | 10 km/h |
| September | 27°C | 12°C | 0°C / 39°C | 17 mm | 47% | 10 km/h |
| October | 18°C | 5°C | -11°C / 32°C | 22 mm | 58% | 10 km/h |
| November | 10°C | 0°C | -23°C / 24°C | 30 mm | 72% | 10 km/h |
| December | 4°C | -3°C | -17°C / 17°C | 38 mm | 81% | 10 km/h |
Best time to visit Boise
The most comfortable time to visit Boise is generally May to June and September, balancing mild daytime temperatures against the driest stretch of the year. The city has strongly marked seasons and rain concentrates around May, totalling about 276 mm a year.
Travellers who prefer heat should aim for July, when highs average 35°C. May is the month to avoid if rain would spoil your plans — it averages 44 mm, roughly 18× the rainfall of the driest month (July).
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Boise forecast for what is happening now.