Mullan, Idaho climate: Normal weather by month, frost dates and records
Mullan's normal year runs from 18°F December nights to 70°F July afternoons, with 45.1 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 3.7°C, December lows of −8°C, July highs of 21°C, 1,145 mm of precipitation a year.
- NOAA stationMullan Pass Vor/Dme
- Station IDUSW00024154
- Location47.46°N 115.64°W
- Elevation6,028 ft (1,837 m)
- Population675
On October 22, the normal high in Mullan is 41°F and the normal low 30°F, and the chance of measurable rain or snow is 47%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Mullan.
- Jan 28° 19°
- Feb 28° 19°
- Mar 34° 22°
- Apr 40° 27°
- May 50° 36°
- Jun 58° 42°
- Jul 70° 52°
- Aug 69° 51°
- Sep 59° 44°
- Oct 44° 32°
- Nov 32° 24°
- Dec 27° 18°
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 Mullan each month?
July is the warmest month, with normal highs of 70°F; December the coldest, with normal lows of 18°F. The most precipitation falls in December (6.04 in), the least in July (1.09 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 28°F | 19°F | 23.3°F | 5.90 | 19 | <1 | 30 | 8 h 50 min |
| February | 28°F | 19°F | 23.5°F | 4.66 | 18 | <1 | 28 | 10 h 10 min |
| March | 34°F | 22°F | 28.3°F | 5.03 | 20 | <1 | 29 | 11 h 50 min |
| April | 40°F | 27°F | 33.8°F | 3.60 | 17 | <1 | 24 | 13 h 30 min |
| May | 50°F | 36°F | 43.0°F | 2.96 | 15 | <1 | 12 | 15 h |
| June | 58°F | 42°F | 50.1°F | 3.12 | 13 | <1 | 3 | 16 h |
| July | 70°F | 52°F | 60.9°F | 1.09 | 6 | <1 | <1 | 15 h 40 min |
| August | 69°F | 51°F | 60.4°F | 1.14 | 6 | <1 | <1 | 14 h 20 min |
| September | 59°F | 44°F | 51.3°F | 1.65 | 8 | <1 | 3 | 12 h 40 min |
| October | 44°F | 32°F | 38.1°F | 3.89 | 13 | <1 | 18 | 11 h |
| November | 32°F | 24°F | 27.7°F | 6.01 | 18 | <1 | 27 | 9 h 20 min |
| December | 27°F | 18°F | 22.4°F | 6.04 | 18 | <1 | 31 | 8 h 30 min |
| Year (annual) | 45°F | 32°F | 38.6°F | 45.09 | 170 | <1 | 206 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −7°C | −4.8°C | 150 mm |
| February | −2°C | −7°C | −4.7°C | 118 mm |
| March | 1°C | −5°C | −2.1°C | 128 mm |
| April | 5°C | −3°C | 1.0°C | 91 mm |
| May | 10°C | 2°C | 6.1°C | 75 mm |
| June | 15°C | 6°C | 10.1°C | 79 mm |
| July | 21°C | 11°C | 16.1°C | 28 mm |
| August | 21°C | 11°C | 15.8°C | 29 mm |
| September | 15°C | 6°C | 10.7°C | 42 mm |
| October | 7°C | 0°C | 3.4°C | 99 mm |
| November | 0°C | −5°C | −2.4°C | 153 mm |
| December | −3°C | −8°C | −5.3°C | 153 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Wallace (13 miles away), gets 76 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024154; 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 Mullan?
Normal highs sit between 65°F and 85°F in July and August. Of those, July has the fewest days with rain (6).
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 USW00024154.
When is the last frost in Mullan?
In Mullan, the last spring frost (32°F) comes after June 10 in half of years and after June 25 in one year in ten; the first autumn frost comes before September 23 in half of years and before September 4 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
- June 101 year in 10 after June 25; 9 in 10 after May 21
- First autumn frost, half of years before
- September 231 year in 10 before September 4; 9 in 10 before October 8
NOAA puts the median frost-free season at 104 days, and the season without a hard freeze (28°F) at 135 days.
A hard freeze (28°F) comes after May 21 in half of springs and before October 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Mullan in zone 6a in ZIP code 83846, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Mullan's NOAA station is in zone 6a: the coldest night of a typical year reaches −7°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 USW00024154; 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 Mullan?
In a normal year in Mullan, a 90°F day is rare, 206 nights fall to 32°F or colder and 170 days bring measurable precipitation.
- Days at 90°F or more
- fewer than 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 206a normal year
- Days that stay below freezing
- 119high of 32°F or less
- Days with 0.01 inch of precipitation
- 170a normal year
The highest temperature in this station's record (since 1938) is 93°F, on August 9, 1942; the lowest is −25°F, on January 13, 2024.
The wettest calendar year on that record is 2017, with 56.49 in; the snowiest season is 1953–54, with 391.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00024154; records: ACIS (NOAA Regional Climate Centers), station USW00024154. Records use complete months only; a month missing more than three days is left out.
How sunny is Mullan?
Over a year 71% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Mullan, 3.7 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (51%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 54% | 1.1 |
| February | 60% | 2.0 |
| March | 62% | 3.2 |
| April | 66% | 4.5 |
| May | 69% | 5.6 |
| June | 71% | 6.2 |
| July | 87% | 7.3 |
| August | 84% | 6.0 |
| September | 77% | 4.2 |
| October | 66% | 2.5 |
| November | 54% | 1.3 |
| December | 51% | 0.9 |
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 Mullan need?
A normal year in Mullan brings 9,714 heating degree days, 81% more than the median U.S. place (5,373), and 102 cooling degree days, 89% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 999 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,291 | 0 |
| February | 1,163 | 0 |
| March | 1,136 | 0 |
| April | 936 | 0 |
| May | 683 | 1 |
| June | 451 | 6 |
| July | 174 | 46 |
| August | 182 | 40 |
| September | 421 | 10 |
| October | 835 | 0 |
| November | 1,119 | 0 |
| December | 1,322 | 0 |
| Year (annual) | 9,714 | 102 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024154. 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 Mullan been warmer than normal lately?
2024 averaged 39.8°F, 1.2°F above the 1991-2020 normal of 38.6°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 39.5°F | +0.9°F | 48.83 |
| 2022 | 38.5°F | −0.1°F | 45.88 |
| 2023 | 39.6°F | +1.0°F | 34.53 |
| 2024 | 39.8°F | +1.2°F | 45.70 |
Source: observed years: ACIS, station USW00024154. A year counts only with all twelve months complete.
How does Mullan's climate compare?
Mullan is warmer than 2 of the other 84 places with their own NOAA record in Idaho, and wetter than 79. Across the 7,247 U.S. stations with normals, its annual mean of 38.6°F is warmer than 4%.
In the Köppen classification computed from these normals, Mullan is Dsb: continental, dry-summer, warm summer. 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.
Which places near Mullan share this climate record?
Saltese has no NOAA station with 1991-2020 normals of its own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Saltese, MT17 people · 7 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Mullan's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Mullan. This page uses Mullan Pass Vor/Dme; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Mullan station USC00106230 | 8 mi W | 3,201 ft | 45.1°F | 23°F | 81°F | 36.6 | – | May 12 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Mullan's climate
What is the coldest month in Mullan?
December, with a normal high of 27°F and a normal low of 18°F. The warmest is July (70°F by day, 52°F at night).
Does it snow in Mullan?
Yes. NOAA publishes no 1991-2020 snowfall normal for Mullan's NOAA station; the nearest record that keeps one, Wallace (13 miles away), records 76 inches of snow in a normal year.
What is the rainiest month in Mullan?
December, with 6.04 in of precipitation in a normal year; the driest is July with 1.09 in.
What plant hardiness zone is Mullan in?
The USDA's 2023 map puts Mullan in zone 6a in ZIP code 83846, the nearest ZIP area. By the same method at Mullan's NOAA station, the coldest night of a typical year reaches −7°F (21 years, 1991-2020): zone 6a.
How late can frost come in Mullan?
In half of years the last 32°F night comes after June 10; in one year in ten it comes after June 25. Waiting until June 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Haugan, MT11 miles from this station, 42.2°F a year
- Wallace, ID14 miles from this station, 46.0°F a year
- Thompson Falls, MT16 miles from this station, 47.7°F a year
- Prichard (3 mi ESE), ID18 miles from this station, 44.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made