Brownlee Dam, Idaho climate: Climate normals at a NOAA weather station
Brownlee Dam's normal year runs from 28°F January nights to 95°F July afternoons, with 14.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.8°C, January lows of −2°C, July highs of 35°C, 377 mm of precipitation a year.
- NOAA stationBrownlee Dam
- Station IDUSC00101180
- Location44.84°N 116.90°W
- Elevation1,844 ft (562 m)
On October 23, the normal high in Brownlee Dam is 62°F and the normal low 42°F, and the chance of measurable rain or snow is 25%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Brownlee Dam.
- Jan 39° 28°
- Feb 45° 30°
- Mar 55° 35°
- Apr 64° 42°
- May 74° 50°
- Jun 83° 56°
- Jul 95° 64°
- Aug 94° 63°
- Sep 83° 55°
- Oct 66° 45°
- Nov 50° 35°
- Dec 40° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Brownlee Dam each month?
July is the warmest month, with normal highs of 95°F; January the coldest, with normal lows of 28°F. The most precipitation falls in December (2.03 in), the least in August (0.23 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 39°F | 28°F | 33.3°F | 1.85 | 13 | <1 | 23 | 9 h 10 min |
| February | 45°F | 30°F | 37.4°F | 1.28 | 9 | <1 | 17 | 10 h 20 min |
| March | 55°F | 35°F | 45.3°F | 1.52 | 11 | <1 | 6 | 11 h 50 min |
| April | 64°F | 42°F | 53.0°F | 1.39 | 11 | <1 | 1 | 13 h 30 min |
| May | 74°F | 50°F | 62.0°F | 1.83 | 10 | 3 | <1 | 14 h 50 min |
| June | 83°F | 56°F | 69.4°F | 1.24 | 8 | 8 | <1 | 15 h 30 min |
| July | 95°F | 64°F | 79.6°F | 0.40 | 3 | 25 | <1 | 15 h 20 min |
| August | 94°F | 63°F | 78.6°F | 0.23 | 2 | 24 | <1 | 14 h 10 min |
| September | 83°F | 55°F | 69.2°F | 0.51 | 3 | 9 | <1 | 12 h 40 min |
| October | 66°F | 45°F | 55.5°F | 1.10 | 7 | <1 | <1 | 11 h |
| November | 50°F | 35°F | 42.3°F | 1.45 | 10 | <1 | 9 | 9 h 40 min |
| December | 40°F | 29°F | 34.2°F | 2.03 | 13 | <1 | 22 | 8 h 50 min |
| Year (annual) | 66°F | 44°F | 55.0°F | 14.83 | 100 | 68 | 79 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 4°C | −2°C | 0.7°C | 47 mm |
| February | 7°C | −1°C | 3.0°C | 33 mm |
| March | 13°C | 2°C | 7.4°C | 39 mm |
| April | 18°C | 5°C | 11.7°C | 35 mm |
| May | 23°C | 10°C | 16.7°C | 46 mm |
| June | 28°C | 13°C | 20.8°C | 31 mm |
| July | 35°C | 18°C | 26.4°C | 10 mm |
| August | 35°C | 17°C | 25.9°C | 6 mm |
| September | 28°C | 13°C | 20.7°C | 13 mm |
| October | 19°C | 7°C | 13.1°C | 28 mm |
| November | 10°C | 2°C | 5.7°C | 37 mm |
| December | 4°C | −2°C | 1.2°C | 52 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Halfway (11 miles away), gets 62 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00101180; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Brownlee Dam?
Normal highs sit between 65°F and 85°F in May, June, September and October. Of those, September has the fewest days with rain (3).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00101180.
When is the last frost at Brownlee Dam?
In Brownlee Dam, the last spring frost (32°F) comes after April 2 in half of years and after April 20 in one year in ten; the first autumn frost comes before November 5 in half of years and before October 24 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 21 year in 10 after April 20; 9 in 10 after March 15
- First autumn frost, half of years before
- November 51 year in 10 before October 24; 9 in 10 before November 19
NOAA puts the median frost-free season at 216 days, and the season without a hard freeze (28°F) at 246 days.
A hard freeze (28°F) comes after March 13 in half of springs and before November 16 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Brownlee Dam in zone 7a in ZIP code 97840, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 8a: the coldest night of a typical year reaches 12°F (18 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00101180; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at Brownlee Dam?
In a normal year in Brownlee Dam, 68 days a year reach 90°F (21 of them 100°F or more), 79 nights fall to 32°F or colder and 100 days bring measurable precipitation.
- Days at 90°F or more
- 68a normal year
- Days at 100°F or more
- 21a normal year
- Nights at 32°F or colder
- 79a normal year
- Days that stay below freezing
- 7high of 32°F or less
- Days with 0.01 inch of precipitation
- 100a normal year
The highest temperature in this station's record (since 1966) is 115°F, on July 13, 2002; the lowest is −13°F, on January 31, 1979.
The wettest calendar year on that record is 1970, with 26.00 in; the snowiest season is 1988–89, with 56.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00101180; records: ACIS (NOAA Regional Climate Centers), station USC00101180. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Brownlee Dam?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds at Brownlee Dam, 4.4 kWh per square metre a day. July is the sunniest month (92%) and December the cloudiest (57%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 61% | 1.6 |
| February | 66% | 2.5 |
| March | 66% | 3.6 |
| April | 74% | 5.3 |
| May | 78% | 6.5 |
| June | 82% | 7.3 |
| July | 92% | 7.8 |
| August | 91% | 6.6 |
| September | 86% | 5.0 |
| October | 78% | 3.2 |
| November | 66% | 1.8 |
| December | 57% | 1.2 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Brownlee Dam record?
A normal year at Brownlee Dam brings 4,922 heating degree days, 8% fewer than the median U.S. place (5,373), and 1,299 cooling degree days, 43% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,703 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 983 | 0 |
| February | 774 | 0 |
| March | 611 | 0 |
| April | 365 | 4 |
| May | 155 | 62 |
| June | 40 | 172 |
| July | 4 | 456 |
| August | 4 | 427 |
| September | 42 | 166 |
| October | 308 | 12 |
| November | 682 | 0 |
| December | 955 | 0 |
| Year (annual) | 4,922 | 1,299 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00101180. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
How does Brownlee Dam's climate compare?
Brownlee Dam is warmer than 84 of the 85 places with their own NOAA record in Idaho, and wetter than 41. Across the 7,247 U.S. stations with normals, its annual mean of 55.0°F is warmer than 60%.
In the Köppen classification computed from these normals, Brownlee Dam is BSk: cold semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Questions about Brownlee Dam's climate
What is the coldest month at Brownlee Dam?
January, with a normal high of 39°F and a normal low of 28°F. The warmest is July (95°F by day, 64°F at night).
Does it snow at Brownlee Dam?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Halfway (11 miles away), records 62 inches of snow in a normal year.
What is the rainiest month at Brownlee Dam?
December, with 2.03 in of precipitation in a normal year; the driest is August with 0.23 in.
What plant hardiness zone is Brownlee Dam in?
The USDA's 2023 map puts Brownlee Dam in zone 7a in ZIP code 97840, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches 12°F (18 years, 1991-2020): zone 8a.
How late can frost come at Brownlee Dam?
In half of years the last 32°F night comes after April 2; in one year in ten it comes after April 20. Waiting until April 20 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Halfway, OR11 miles from this station, 47.9°F a year
- Richland, OR14 miles from this station, 49.5°F a year
- Cambridge, ID21 miles from this station, 48.3°F a year
- Council, ID24 miles from this station, 49.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made