Boise in September
In September, Boise averages 28°C (82°F) during the day and 13°C (55°F) at night, with only about 3 rainy days.
ShoulderConditions are warm and beach-friendly. Skies are generally dry and clear.
It's peak hurricane season in Boise during September. Travel is possible but expect storm risk, possible flight disruption, and generally lower travel insurance coverage.
How September compares to the rest of the year in Boise
September is in the middle of the year for warmth in Boise (4th of 12) and one of the driest months (10th of 12). Daytime temperature runs 9°C above the annual average (19°C). September runs 6°C cooler than August (34°C) and cools 9°C in October (19°C).
September sunrise & sunset in Boise
Times shown for Boise local time (America/Boise), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Boise — September
Golden-hour and blue-hour windows for the 15th of September, in Boise's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Boise in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (Shoulder) and Boise's popularity.
Crowds & pricing — September in Boise
Boise is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Why this tier: excellent tourism weather peak hazard season (1 active)
Sun & mosquito risk — September in Boise
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Boise in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 4°C / 40°F | -4°C / 26°F | 43 mm | 10 | — |
| February | 8°C / 46°F | -2°C / 29°F | 38 mm | 9 | — |
| March | 13°C / 56°F | 2°C / 35°F | 39 mm | 9 | — |
| April | 18°C / 64°F | 4°C / 40°F | 31 mm | 7 | — |
| May | 23°C / 74°F | 9°C / 48°F | 39 mm | 8 | — |
| June | 29°C / 84°F | 14°C / 57°F | 22 mm | 3 | — |
| July | 35°C / 95°F | 19°C / 65°F | 2 mm | 1 | — |
| August | 34°C / 92°F | 18°C / 64°F | 5 mm | 1 | — |
| September | 28°C / 82°F | 13°C / 55°F | 15 mm | 3 | — |
| October | 19°C / 66°F | 7°C / 44°F | 26 mm | 5 | — |
| November | 10°C / 50°F | 0°C / 33°F | 37 mm | 8 | — |
| December | 4°C / 39°F | -3°C / 26°F | 55 mm | 12 | — |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Boise in September →
Frequently asked questions
How hot is Boise in September?
In September, Boise averages a high of 28°C (82°F) and a low of 13°C (55°F) — generally warm.
Does it rain a lot in Boise in September?
September is generally dry in Boise, with about 3 rainy days on average.
Is September a good time to visit Boise?
September is warm and mostly dry. It suits travelers who are comfortable with warm weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Boise in September?
Pack lightweight, breathable clothing, sunglasses and sunscreen. See the full September packing list for Boise for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.