Boise, Idaho Weather
Pikas hayfeeding in granite peaks. Day 77 of spring. Read this microseason across nine climate regions →
Boise weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——79°58°—
- FridayJun 5Overcast——88°53°+9°
- SaturdayJun 6Overcast——71°58°-17°
- SundayJun 7Overcast——69°48°-2°
- MondayJun 8Light Rain—0.11″75°57°+6°
- TuesdayJun 9Drizzle45%0.15″61°57°-14°
- WednesdayJun 10Light Drizzle30%0.02″77°55°+16°
PM2.5 at 9.4 µg/m³, PM10 at 13.0 µg/m³ — typical background levels with no transport signature. AQI up 8 over the last 6 hours (gradual rise).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 49 now. With UV 8.9 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 58 by mid-afternoon.
- Present
- AQI 49
- UV peak
- 8.9 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 58
PM × Wind × Precip
PM2.5 at 9.4 µg/m³, PM10 at 13.0 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.72
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 6:29 AM
- Moonset
- 3:39 PM
- In sign
- ♒︎ Aquarius
Pikas hayfeeding in granite peaks
Boise at a glance
- Today vs. normal: 73°F — typical for the season
- Last frost: May 8 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Warm-season window is open
As of June 4, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
July brings Boise's warmest temperatures (~77°F mean) while December delivers the coldest (~32°F). December also brings peak rainfall at 1.5 inches, contrasting sharply with August's dry 0.2 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 32° | 1.4″ | 5 |
| February | 38° | 1.0″ | 4 |
| March | 45° | 1.3″ | 5 |
| April | 51° | 1.2″ | 4 |
| May | 60° | 1.4″ | 4 |
| June | 68° | 0.8″ | 2 |
| July | 77° | 0.2″ | 1 |
| August | 76° | 0.2″ | 0 |
| September | 66° | 0.4″ | 1 |
| October | 53° | 0.8″ | 2 |
| November | 40° | 1.2″ | 4 |
| December | 32° | 1.5″ | 5 |
Regional context
Located within a warm-summer Mediterranean climate region, Boise shares temperature ranges, seasonal patterns, and growing conditions with other nearby cities in this climate zone.
Similar climates: Nampa, ID, Coeur d'Alene, ID, Meridian, ID, Caldwell, ID, Post Falls, ID.
Naturalist notes
Mountain bluebirds return to the Boise area in late March, their azure wings catching the strengthening spring light.
Chokecherry trees bloom throughout the foothills in late April, their white flower clusters marking the transition from cool to warm season.
Frequently asked
- When does it freeze in Boise?
- Boise's last spring frost typically falls around mid-May, while the first fall frost arrives around mid-October.
- What is the rainy season in Boise?
- December brings the most moisture with about 1.5 inches of rain on average; the city receives roughly 12 inches annually.
- What is the warmest month in Boise?
- July typically delivers the warmest weather, averaging about 77°F.
- What is the coldest month in Boise?
- December typically brings the coldest temperatures, averaging about 32°F.
- When can I start a vegetable garden in Boise?
- Cool-season crops (peas, lettuce) can be planted around the last spring frost (mid-May); warm-season crops (tomatoes, peppers) should wait until 1–2 weeks after.
- How many rainy days does Boise get?
- Boise averages about 38 rainy days per year.
- What hardiness zone is Boise?
- Boise's USDA hardiness zone depends on its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Boise, Idaho experiences a warm-summer Mediterranean climate. January temperatures hover near 32°F while July averages 77°F — a 45°F seasonal swing.
Throughout the year, Boise receives about 12 inches of precipitation spread over roughly 38 rainy days.
Location shapes the weather patterns here: latitude (43.6°N), proximity to large water bodies, and elevation determine what grows, when frost arrives, and daily weather conditions.