Weather in Boise, Idaho
High country wildflowers peak. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 16Overcast—60°48°
- SundayMay 17Overcast—60°41°
- MondayMay 18Overcast—66°38°
- TuesdayMay 19Overcast—71°49°
- WednesdayMay 20Overcast—71°49°
- ThursdayMay 21Partly Cloudy—74°51°
- FridayMay 22Mostly Clear—81°58°
- PM 2.5
- 2.0 μg/m³
- PM 10
- 2.6 μg/m³
- NO₂
- 1.0 μg/m³
- Ozone
- 100.0 μg/m³
- UV Index
- 0.1 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 12:23 PM
- Moonset
- 3:44 AM
- In sign
- ♊︎ Gemini
High country wildflowers peak
Boise at a glance
- Today vs. normal: 14°F below the seasonal normal for this latitude
- Last frost: May 8 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Cool-season window is open
As of May 17, the cool-season window is open or about to open. Direct-sow peas, lettuce, spinach, radishes, and brassicas now. Hold off on warm-season crops until 1–2 weeks after the last spring frost (around May).
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.