Libby, Montana climate: Normal weather by month, frost dates and records
Libby's normal year runs from 21°F December nights to 87°F July afternoons. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.4°C, December lows of −6°C, July highs of 30°C.
- NOAA stationLibby
- Station IDUSC00245000
- Location48.38°N 115.56°W
- Elevation2,140 ft (652 m)
- Population3,235
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Libby.
- Jan 32° 21°
- Feb 37° 21°
- Mar 48° 27°
- Apr 58° 31°
- May 69° 40°
- Jun 76° 46°
- Jul 87° 49°
- Aug 84° 48°
- Sep 72° 40°
- Oct 55° 32°
- Nov 38° 27°
- Dec 31° 21°
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 Libby each month?
July is the warmest month, with normal highs of 87°F; December the coldest, with normal lows of 21°F.
| Month | High | Low | Mean | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|
| January | 32°F | 21°F | 26.6°F | – | <1 | 30 | 8 h 40 min |
| February | 37°F | 21°F | 29.3°F | – | <1 | 27 | 10 h 10 min |
| March | 48°F | 27°F | 37.2°F | – | <1 | 27 | 11 h 50 min |
| April | 58°F | 31°F | 44.6°F | – | <1 | 19 | 13 h 40 min |
| May | 69°F | 40°F | 54.3°F | – | 1 | 8 | 15 h 10 min |
| June | 76°F | 46°F | 60.6°F | – | 2 | <1 | 16 h |
| July | 87°F | 49°F | 67.9°F | – | 12 | <1 | 15 h 40 min |
| August | 84°F | 48°F | 66.2°F | – | 8 | <1 | 14 h 20 min |
| September | 72°F | 40°F | 56.0°F | – | 1 | 4 | 12 h 40 min |
| October | 55°F | 32°F | 43.5°F | – | <1 | 15 | 11 h |
| November | 38°F | 27°F | 32.7°F | – | <1 | 23 | 9 h 20 min |
| December | 31°F | 21°F | 26.1°F | – | <1 | 30 | 8 h 20 min |
| Year (annual) | 57°F | 34°F | 45.4°F | – | 23 | 182 |
The same normals in °C and millimetres
| Month | High | Low | Mean |
|---|---|---|---|
| January | 0°C | −6°C | −3.0°C |
| February | 3°C | −6°C | −1.5°C |
| March | 9°C | −3°C | 2.9°C |
| April | 15°C | 0°C | 7.0°C |
| May | 21°C | 4°C | 12.4°C |
| June | 24°C | 8°C | 15.9°C |
| July | 30°C | 10°C | 19.9°C |
| August | 29°C | 9°C | 19.0°C |
| September | 22°C | 5°C | 13.3°C |
| October | 13°C | 0°C | 6.4°C |
| November | 4°C | −3°C | 0.4°C |
| December | 0°C | −6°C | −3.3°C |
NOAA publishes no 1991-2020 snowfall normal for this station. Libby's own co-op station Libby 1 NE Ranger Station does: 48 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USC00245000; 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 Libby?
Normal highs sit between 65°F and 85°F in May, June, August and September.
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 USC00245000.
When is the last frost in Libby?
In Libby, the last spring frost (32°F) comes after May 10 in half of years and after May 26 in one year in ten; the first autumn frost comes before September 26 in half of years and before September 11 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 101 year in 10 after May 26; 9 in 10 after April 28
- First autumn frost, half of years before
- September 261 year in 10 before September 11; 9 in 10 before October 12
NOAA puts the median frost-free season at 137 days, and the season without a hard freeze (28°F) at 166 days.
A hard freeze (28°F) comes after April 27 in half of springs and before October 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Libby in zone 6a in ZIP code 59923, the nearest ZIP area.
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00245000; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Libby?
In a normal year in Libby, 23 days a year reach 90°F (2 of them 100°F or more) and 182 nights fall to 32°F or colder.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 182a normal year
- Days that stay below freezing
- 38high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00245000.
How sunny is Libby?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Libby, 3.6 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (50%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 54% | 1.1 |
| February | 62% | 2.0 |
| March | 62% | 3.1 |
| April | 65% | 4.4 |
| May | 68% | 5.5 |
| June | 69% | 6.0 |
| July | 85% | 7.1 |
| August | 83% | 5.8 |
| September | 75% | 4.0 |
| October | 65% | 2.4 |
| November | 53% | 1.2 |
| December | 50% | 0.8 |
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 Libby need?
A normal year in Libby brings 7,344 heating degree days, 37% more than the median U.S. place (5,373), and 234 cooling degree days, 74% 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 1,774 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,190 | 0 |
| February | 1,000 | 0 |
| March | 862 | 0 |
| April | 611 | 0 |
| May | 335 | 3 |
| June | 150 | 18 |
| July | 31 | 119 |
| August | 52 | 89 |
| September | 276 | 6 |
| October | 667 | 0 |
| November | 968 | 0 |
| December | 1,206 | 0 |
| Year (annual) | 7,344 | 234 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00245000. 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 Libby been warmer than normal lately?
2025 averaged 48.4°F, 3.0°F above the 1991-2020 normal of 45.4°F.
| Year | Mean | Against normal |
|---|---|---|
| 2025 | 48.4°F | +3.0°F |
Source: observed years: ACIS, station USC00245000. A year counts only with all twelve months complete.
How does Libby's climate compare?
Libby is warmer than 101 of the other 140 places with their own NOAA record in Montana. Across the 7,247 U.S. stations with normals, its annual mean of 45.4°F is warmer than 21%.
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers.
Which places near Libby share this climate record?
2 places have no NOAA station with 1991-2020 normals of their 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.
- Pioneer Junction, MT734 people · 5 mi S
- White Haven, MT660 people · 3 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 Libby's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near Libby. This page uses Libby; the others differ by site and elevation, and the linked ones have pages of their own:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Libby Dam (Base) USC00245011 | 11 mi E | 2,110 ft | 46.4°F | 22°F | 85°F | 17.1 | – | May 11 |
| Libby 1 NE Ranger Station USC00245015 | 2 mi NE | 2,096 ft | 47.4°F | 22°F | 89°F | 19.1 | 48 | May 23 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Libby's climate
What is the coldest month in Libby?
December, with a normal high of 31°F and a normal low of 21°F. The warmest is July (87°F by day, 49°F at night).
Does it snow in Libby?
Yes. NOAA publishes no 1991-2020 snowfall normal for Libby's NOAA station; Libby's own co-op station Libby 1 NE Ranger Station records 48 inches of snow in a normal year.
What plant hardiness zone is Libby in?
The USDA's 2023 map puts Libby in zone 6a in ZIP code 59923, the nearest ZIP area.
How late can frost come in Libby?
In half of years the last 32°F night comes after May 10; in one year in ten it comes after May 26. Waiting until May 26 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Libby Dam (Base), MT11 miles from this station, 46.4°F a year
- Troy, MT17 miles from this station, 46.8°F a year
- Heron, MT29 miles from this station, 45.1°F a year
- Cabinet Gorge, ID30 miles from this station, 46.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made