Salmon, Idaho climate: Normal weather by month, frost dates and records
Salmon's normal year runs from 11°F January nights to 86°F July afternoons, with 9.5 inches of precipitation and 22 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.9°C, January lows of −12°C, July highs of 30°C, 241 mm of precipitation a year.
- NOAA stationSalmon-Ksra
- Station IDUSC00108080
- Location45.17°N 113.89°W
- Elevation3,953 ft (1,205 m)
- Population3,257
On October 14, the normal high in Salmon is 60°F and the normal low 31°F, and the chance of measurable rain or snow is 18%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Salmon.
- Jan 28° 11°
- Feb 36° 16°
- Mar 50° 26°
- Apr 59° 32°
- May 68° 40°
- Jun 76° 46°
- Jul 86° 52°
- Aug 85° 49°
- Sep 74° 41°
- Oct 58° 31°
- Nov 41° 22°
- Dec 29° 13°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Salmon each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 11°F. The most precipitation falls in June (1.63 in), the least in February (0.37 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 28°F | 11°F | 19.6°F | 0.58 | 6.7 | 6 | <1 | 31 | 9 h 10 min |
| February | 36°F | 16°F | 26.0°F | 0.37 | 3.8 | 5 | <1 | 28 | 10 h 20 min |
| March | 50°F | 26°F | 37.5°F | 0.47 | 1.2 | 6 | <1 | 26 | 11 h 50 min |
| April | 59°F | 32°F | 45.2°F | 0.77 | 0.4 | 7 | <1 | 15 | 13 h 30 min |
| May | 68°F | 40°F | 54.0°F | 1.29 | 0.1 | 9 | <1 | 4 | 14 h 50 min |
| June | 76°F | 46°F | 61.0°F | 1.63 | 0.0 | 9 | 3 | <1 | 15 h 40 min |
| July | 86°F | 52°F | 69.0°F | 0.77 | 0.0 | 6 | 12 | <1 | 15 h 20 min |
| August | 85°F | 49°F | 66.7°F | 0.60 | 0.0 | 5 | 9 | <1 | 14 h 10 min |
| September | 74°F | 41°F | 57.4°F | 0.79 | 0.0 | 5 | 1 | 2 | 12 h 40 min |
| October | 58°F | 31°F | 44.6°F | 0.81 | 0.1 | 6 | <1 | 17 | 11 h |
| November | 41°F | 22°F | 31.2°F | 0.67 | 3.3 | 6 | <1 | 27 | 9 h 40 min |
| December | 29°F | 13°F | 20.9°F | 0.73 | 6.4 | 7 | <1 | 31 | 8 h 50 min |
| Year (annual) | 58°F | 31°F | 44.4°F | 9.48 | 22.0 | 78 | 25 | 180 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −12°C | −6.9°C | 15 mm | 17 cm |
| February | 2°C | −9°C | −3.3°C | 9 mm | 10 cm |
| March | 10°C | −4°C | 3.1°C | 12 mm | 3 cm |
| April | 15°C | 0°C | 7.3°C | 20 mm | 1 cm |
| May | 20°C | 4°C | 12.2°C | 33 mm | 0 cm |
| June | 24°C | 8°C | 16.1°C | 41 mm | 0 cm |
| July | 30°C | 11°C | 20.6°C | 20 mm | 0 cm |
| August | 29°C | 9°C | 19.3°C | 15 mm | 0 cm |
| September | 24°C | 5°C | 14.1°C | 20 mm | 0 cm |
| October | 15°C | −1°C | 7.0°C | 21 mm | 0 cm |
| November | 5°C | −6°C | −0.4°C | 17 mm | 8 cm |
| December | −2°C | −11°C | −6.2°C | 19 mm | 16 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00108080; 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.
When is the best weather to visit Salmon?
Normal highs sit between 65°F and 85°F in May, June, August and September. Of those, September has the fewest days with rain (5).
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 USC00108080.
When is the last frost in Salmon?
In Salmon, the last spring frost (32°F) comes after May 17 in half of years and after June 9 in one year in ten; the first autumn frost comes before September 24 in half of years and before September 9 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
- May 171 year in 10 after June 9; 9 in 10 after May 3
- First autumn frost, half of years before
- September 241 year in 10 before September 9; 9 in 10 before October 5
NOAA puts the median frost-free season at 127 days, and the season without a hard freeze (28°F) at 153 days.
A hard freeze (28°F) comes after May 2 in half of springs and before October 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Salmon in zone 5b in ZIP code 83467, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Salmon's NOAA station is in zone 5b: the coldest night of a typical year reaches −10°F (21 complete years).
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00108080; 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 in Salmon?
In a normal year in Salmon, 25 days a year reach 90°F (1 of them 100°F or more), 180 nights fall to 32°F or colder and 78 days bring measurable precipitation.
- Days at 90°F or more
- 25a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 180a normal year
- Days that stay below freezing
- 53high of 32°F or less
- Days with 0.01 inch of precipitation
- 78a normal year
- Days with 1 inch of snow or more
- 9a normal year
The highest temperature in Salmon's official record (kept by the National Weather Service since 1905) is 106°F, on July 21, 1936; the lowest is −37°F, on January 21, 1937.
The wettest calendar year on that record is 1977, with 14.75 in; the snowiest season is 1983–84, with 56.2 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00108080; records: ACIS (NOAA Regional Climate Centers), NWS threaded record SLNI1thr. Records use complete months only; a month missing more than three days is left out.
How sunny is Salmon?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Salmon, 4.2 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 70% | 1.7 |
| February | 73% | 2.8 |
| March | 73% | 4.0 |
| April | 70% | 5.1 |
| May | 70% | 5.9 |
| June | 76% | 6.8 |
| July | 85% | 7.3 |
| August | 84% | 6.2 |
| September | 80% | 4.7 |
| October | 73% | 3.0 |
| November | 68% | 1.9 |
| December | 65% | 1.4 |
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 much heating and cooling does Salmon need?
A normal year in Salmon brings 7,765 heating degree days, 45% more than the median U.S. place (5,373), and 293 cooling degree days, 68% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,911 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,407 | 0 |
| February | 1,091 | 0 |
| March | 853 | 0 |
| April | 596 | 0 |
| May | 344 | 3 |
| June | 156 | 35 |
| July | 26 | 148 |
| August | 43 | 97 |
| September | 236 | 10 |
| October | 633 | 0 |
| November | 1,014 | 0 |
| December | 1,367 | 0 |
| Year (annual) | 7,765 | 293 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00108080. 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.
Has Salmon been warmer than normal lately?
2025 averaged 46.8°F, 2.4°F above the 1991-2020 normal of 44.4°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 45.5°F | +1.1°F | 6.06 | 18.5 |
| 2023 | 44.2°F | −0.2°F | 10.79 | – |
| 2024 | 46.7°F | +2.3°F | 8.10 | 23.0 |
| 2025 | 46.8°F | +2.4°F | 9.83 | 40.0 |
Over 93 complete years from 1907 to 2025, the station's annual mean temperature rose at a fitted 1.7°F per century (+0.10°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00108080; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Salmon's climate compare?
Salmon is warmer than 26 of the other 84 places with their own NOAA record in Idaho, and wetter than 5. Across the 7,247 U.S. stations with normals, its annual mean of 44.4°F is warmer than 17%.
In the Köppen classification computed from these normals, Salmon 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 Salmon's climate
What is the coldest month in Salmon?
January, with a normal high of 28°F and a normal low of 11°F. The warmest is July (86°F by day, 52°F at night).
Does it snow in Salmon?
Yes: 22 inches in a normal year, falling on 15 days with 0.1 inch or more, the most in January (6.7 inches).
What is the rainiest month in Salmon?
June, with 1.63 in of precipitation in a normal year; the driest is February with 0.37 in.
What plant hardiness zone is Salmon in?
The USDA's 2023 map puts Salmon in zone 5b in ZIP code 83467, the nearest ZIP area. By the same method at Salmon's NOAA station, the coldest night of a typical year reaches −10°F (21 years, 1991-2020): zone 5b.
How late can frost come in Salmon?
In half of years the last 32°F night comes after May 17; in one year in ten it comes after June 9. Waiting until June 9 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Shoup, ID24 miles from this station, 47.8°F a year
- Gibbonsville #2, ID26 miles from this station, 42.2°F a year
- Jackson, MT27 miles from this station, 36.8°F a year
- Wisdom, MT37 miles from this station, 35.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made