Boise, ID Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Boise's primary NOAA station, BOISE 7 N.
The climate verdict for Boise
Dryness leads the climate profile for Boise, Idaho, with 18.0 inches of precipitation a year. NOAA records an annual average of 50°F. At 44/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 10% of scores.
- 50°F
- yearly average temperature, NOAA normal
- 44/100
- comfort score, above 10% of station-mapped location scores
- 18.0"
- annual precipitation · 57" snow
- 148 days
- growing season, frost-free days
Boise: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00101017 · Boise, ID 50°F mean · 18.0" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 50°F
- RANK-COOL #2,676
- PHOTO-FINISH ≈ Middletown
- PRCP-DRY 18.0"
- SWING-MID 43°F
- COMF-LOW 44/100
- LOAD-HEAT 6,167 HDD
- STN-1 USC00101017
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Middletown, NY ( -0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every ID station list.
- Boise (this station) 50°F
- Cold Middletown, NY 50°F
- Hot Rome St, OR 50°F
- Near Blue Hill, MA 50°F
- Near Benton Harbor, MI 50°F
Climate Living Index · Boise
Boise: 42/100 · grade D
Boise publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Boise, not an official NOAA rating. Rankings still use Comfort Score 44/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 125 calendar days | 62/100 · C |
| Precipitation balance | 18.0 in · 17.0 from 35 in | 40/100 · D |
| Annual temperature balance | 49.8°F · 17.7° from 67.5°F | 39/100 · F |
| Frost-free season | 148 days/year | 24/100 · F |
| Snowfall burden | 57.4 inches/year | 17/100 · F |
Boise · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Boise is a continental Köppen climate: Dsa
Coldest-month mean 30.1°F and warmest-month mean 72.7°F place this station in continental, dry-summer, hot summer climates (Dsa). Class Dsa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, dry-summer, hot summer.
- Köppen code
- Dsa
- Group
- Continental
- Warmest month
- 72.7°F
- Coldest month
- 30.1°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Boise sits across the climate record
Three NOAA fields for Boise's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 39th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 76%
- Boise's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 47th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Boise compares across U.S. station-mapped locations
Boise's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
44 10th percentile score exceeds 10% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Boise's measured station temperature trend
MethodologyAcross 45 complete annual observations from 1974 to 2024, BOISE 7 N warmed at a fitted rate of 0.27°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Boise primary station fitted change +0.27 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 37°F (3°C) | 24°F (-5°C) | 30°F (-1°C) | 2.3" | 14.0" | 26.7 | 0.0 |
| February | 43°F (6°C) | 27°F (-3°C) | 35°F (1°C) | 1.6" | 9.2" | 20.6 | 0.0 |
| March | 51°F (11°C) | 32°F (0°C) | 42°F (5°C) | 2.1" | 6.6" | 15.4 | 0.0 |
| April | 58°F (14°C) | 36°F (2°C) | 47°F (8°C) | 1.9" | 2.4" | 9.3 | 0.0 |
| May | 68°F (20°C) | 43°F (6°C) | 55°F (13°C) | 2.1" | 0.7" | 3.1 | 0.1 |
| June | 77°F (25°C) | 49°F (9°C) | 63°F (17°C) | 1.1" | 0.1" | 0.3 | 2.6 |
| July | 88°F (31°C) | 58°F (14°C) | 73°F (23°C) | 0.3" | 0.0" | 0.0 | 13.8 |
| August | 86°F (30°C) | 58°F (14°C) | 72°F (22°C) | 0.2" | 0.0" | 0.0 | 11.1 |
| September | 76°F (24°C) | 50°F (10°C) | 63°F (17°C) | 0.6" | 0.0" | 0.4 | 1.4 |
| October | 61°F (16°C) | 40°F (4°C) | 51°F (10°C) | 1.2" | 0.4" | 5.4 | 0.0 |
| November | 46°F (8°C) | 30°F (-1°C) | 38°F (3°C) | 2.0" | 7.3" | 17.7 | 0.0 |
| December | 37°F (3°C) | 23°F (-5°C) | 30°F (-1°C) | 2.6" | 16.7" | 26.2 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 90°F around July 26, short of 90°F on every date, while 125 dates carry a normal low at or below freezing, the coldest 22°F near December 22.
The freezing stretch
The normal low stays at or below 32°F into March 12, then returns to freezing around November 9, covering 125 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is December 7, when 45% of years recorded at least a hundredth of an inch. The driest is August 5 at 9%. Summed across the calendar, that is about 112 wet dates a year.
The widest day
July 16 carries the biggest normal gap between afternoon and dawn, 30°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Boise.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 14.0"
13.5 days with precipitation
Snow: 9.2"
11.7 days with precipitation
Snow: 6.6"
12.6 days with precipitation
Snow: 2.4"
11.4 days with precipitation
Snow: 0.7"
10.6 days with precipitation
Snow: 0.1"
7.4 days with precipitation
3.5 days with precipitation
2.5 days with precipitation
4.8 days with precipitation
Snow: 0.4"
7.5 days with precipitation
Snow: 7.3"
11.9 days with precipitation
Snow: 16.7"
14.0 days with precipitation
Boise's wet season runs through the cold months
December, January and February carry 36% of the year's precipitation here, while June through August contribute 9%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows a 42.6°F seasonal spread.
- Wettest month
- December, 2.6"
- Driest month
- August, 0.2"
- Wettest three months
- December, January, May (39% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
Boise is dry, and what does fall arrives gently
Only about 111 days a year record measurable precipitation here, 31% of the calendar, and they carry 18.0" between them. At roughly 0.16 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is December at about 14 wet days; the driest is August at about 3.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Winter brings real snow to Boise
Boise averages 57.4 inches of snowfall a year, with December the snowiest month on the normals, spread across roughly 38 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 57.4 inches of depth.
- Days recording measurable snow: about 38 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 32% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
October 12
50% probability date
Last Spring Freeze
May 17
50% probability date
Growing Season
148 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,167
Higher = more heating needed
Cooling Degree Days
648
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside ID closest to Boise on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (50°F here).
- Allerton, IA 50°F · 0.0°F off
- Blowing Rock, NC 50°F · 0.0°F off
- Boswell, IN 50°F · 0.0°F off
- Cambridge City, IN 50°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (18.0" here), excluding temperature-peer places.
- Dayton, WY 18.0" · 0.0" off
- Underwood, ND 18.0" · 0.0" off
- Brownfield, TX 18.1" · 0.0" off
- Hemingford, NE 18.0" · 0.0" off
Snow and freeze rhythm
When cold and snow define Boise
heating led · dry · mid swing
Boise's energy balance leans toward cold weather: 6,167 annual heating degree days against 648 for cooling. Its 42.6°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 148 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
-
1. Boise coldest normal
December
The monthly mean of 30°F (-1°C) sits near freezing, so cold nights and above-freezing afternoons share the same month.
-
2. Boise typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Boise snow peak
December
Boise averages 57.4 inches of snow a year, with December the snowiest month on the normals.
Questions about Boise's climate
How much snow does Boise get? ▼
How cold does Boise get in winter? ▼
How much energy does heating and cooling require in Boise? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Boise's primary station: BOISE 7 N (USC00101017). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Boise; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Boise comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.