Mystic Lake, Montana climate: Climate normals at a NOAA weather station
Mystic Lake's normal year runs from 18°F December nights to 75°F July afternoons, with 26.5 inches of precipitation and 193 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.3°C, December lows of −8°C, July highs of 24°C, 673 mm of precipitation a year.
- NOAA stationMystic Lake
- Station IDUSC00245961
- Location45.24°N 109.73°W
- Elevation6,544 ft (1,995 m)
On October 22, the normal high in Mystic Lake is 49°F and the normal low 31°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Mystic Lake.
- Jan 35° 19°
- Feb 34° 17°
- Mar 41° 22°
- Apr 48° 27°
- May 57° 35°
- Jun 66° 43°
- Jul 75° 50°
- Aug 74° 50°
- Sep 66° 42°
- Oct 52° 32°
- Nov 40° 24°
- Dec 33° 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 at Mystic Lake each month?
July is the warmest month, with normal highs of 75°F; December the coldest, with normal lows of 18°F. The most precipitation falls in May (4.10 in), the least in January (1.12 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 35°F | 19°F | 26.5°F | 1.12 | 17.4 | 8 | <1 | 26 | 9 h 10 min |
| February | 34°F | 17°F | 25.6°F | 1.49 | 25.3 | 9 | <1 | 25 | 10 h 20 min |
| March | 41°F | 22°F | 31.8°F | 2.00 | 31.6 | 11 | <1 | 26 | 11 h 50 min |
| April | 48°F | 27°F | 37.4°F | 2.73 | 34.0 | 12 | <1 | 21 | 13 h 30 min |
| May | 57°F | 35°F | 45.7°F | 4.10 | 14.6 | 14 | <1 | 11 | 14 h 50 min |
| June | 66°F | 43°F | 54.3°F | 3.01 | 1.7 | 14 | <1 | 2 | 15 h 40 min |
| July | 75°F | 50°F | 62.3°F | 2.30 | 0.0 | 12 | <1 | <1 | 15 h 20 min |
| August | 74°F | 50°F | 61.9°F | 1.86 | 0.0 | 12 | <1 | <1 | 14 h 10 min |
| September | 66°F | 42°F | 53.6°F | 2.03 | 3.8 | 9 | <1 | 4 | 12 h 40 min |
| October | 52°F | 32°F | 42.1°F | 2.55 | 20.1 | 10 | <1 | 15 | 11 h |
| November | 40°F | 24°F | 32.0°F | 1.92 | 22.6 | 9 | <1 | 21 | 9 h 30 min |
| December | 33°F | 18°F | 25.3°F | 1.40 | 21.6 | 10 | <1 | 28 | 8 h 50 min |
| Year (annual) | 52°F | 31°F | 41.6°F | 26.51 | 192.7 | 131 | <1 | 178 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 1°C | −7°C | −3.1°C | 28 mm | 44 cm |
| February | 1°C | −8°C | −3.6°C | 38 mm | 64 cm |
| March | 5°C | −5°C | −0.1°C | 51 mm | 80 cm |
| April | 9°C | −3°C | 3.0°C | 69 mm | 86 cm |
| May | 14°C | 2°C | 7.6°C | 104 mm | 37 cm |
| June | 19°C | 6°C | 12.4°C | 76 mm | 4 cm |
| July | 24°C | 10°C | 16.8°C | 58 mm | 0 cm |
| August | 23°C | 10°C | 16.6°C | 47 mm | 0 cm |
| September | 19°C | 5°C | 12.0°C | 52 mm | 10 cm |
| October | 11°C | 0°C | 5.6°C | 65 mm | 51 cm |
| November | 4°C | −4°C | 0.0°C | 49 mm | 57 cm |
| December | 0°C | −8°C | −3.7°C | 36 mm | 55 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00245961; 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 Mystic Lake?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, September has the fewest days with rain (9).
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 USC00245961.
When is the last frost at Mystic Lake?
In Mystic Lake, the last spring frost (32°F) comes after June 5 in half of years and after June 21 in one year in ten; the first autumn frost comes before September 14 in half of years and before August 31 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 51 year in 10 after June 21; 9 in 10 after May 22
- First autumn frost, half of years before
- September 141 year in 10 before August 31; 9 in 10 before September 28
NOAA puts the median frost-free season at 99 days, and the season without a hard freeze (28°F) at 122 days.
A hard freeze (28°F) comes after May 24 in half of springs and before September 25 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Mystic Lake in zone 5a in ZIP code 59028, 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 5a: the coldest night of a typical year reaches −17°F (29 complete years).
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00245961; 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 Mystic Lake?
In a normal year in Mystic Lake, a 90°F day is rare, 178 nights fall to 32°F or colder and 131 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
- 178a normal year
- Days that stay below freezing
- 50high of 32°F or less
- Days with 0.01 inch of precipitation
- 131a normal year
- Days with 1 inch of snow or more
- 53a normal year
The highest temperature in this station's record (since 1924) is 95°F, on July 13, 2026; the lowest is −38°F, on February 3, 1989.
The wettest calendar year on that record is 2019, with 35.64 in; the snowiest season is 2017–18, with 322.2 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00245961; records: ACIS (NOAA Regional Climate Centers), station USC00245961. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Mystic Lake?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds at Mystic Lake, 4.1 kWh per square metre a day. July is the sunniest month (85%) and April the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 75% | 1.9 |
| February | 76% | 2.8 |
| March | 70% | 3.8 |
| April | 66% | 4.7 |
| May | 69% | 5.7 |
| June | 77% | 6.7 |
| July | 85% | 7.1 |
| August | 84% | 6.0 |
| September | 80% | 4.6 |
| October | 72% | 2.9 |
| November | 70% | 1.9 |
| December | 67% | 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 many heating and cooling degree days does Mystic Lake record?
A normal year at Mystic Lake brings 8,605 heating degree days, 60% more than the median U.S. place (5,373), and 81 cooling degree days, 91% 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 1,215 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,194 | 0 |
| February | 1,103 | 0 |
| March | 1,029 | 0 |
| April | 826 | 0 |
| May | 599 | 0 |
| June | 324 | 4 |
| July | 119 | 37 |
| August | 132 | 34 |
| September | 348 | 6 |
| October | 709 | 0 |
| November | 992 | 0 |
| December | 1,232 | 0 |
| Year (annual) | 8,605 | 81 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00245961. 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.
Have recent years at Mystic Lake been warmer than normal?
2025 averaged 43.9°F, 2.3°F above the 1991-2020 normal of 41.6°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 43.1°F | +1.5°F | 19.35 | 220.1 |
| 2023 | 42.7°F | +1.1°F | 30.37 | 177.7 |
| 2024 | 44.7°F | +3.1°F | 22.56 | 171.4 |
| 2025 | 43.9°F | +2.3°F | 31.92 | 207.6 |
Over 86 complete years from 1926 to 2025, the station's annual mean temperature rose at a fitted 3.1°F per century (+0.17°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00245961; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Mystic Lake's climate compare?
Mystic Lake is warmer than 25 of the 141 places with their own NOAA record in Montana, and wetter than 127. Across the 7,247 U.S. stations with normals, its annual mean of 41.6°F is warmer than 9%.
In the Köppen classification computed from these normals, Mystic Lake is Dfb: continental, no dry season, 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 Mystic Lake share this climate record?
Roscoe 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.
- Roscoe, MT24 people · 14 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Mystic Lake's climate
What is the coldest month at Mystic Lake?
December, with a normal high of 33°F and a normal low of 18°F. The warmest is July (75°F by day, 50°F at night).
Does it snow at Mystic Lake?
Yes: 193 inches in a normal year, falling on 60 days with 0.1 inch or more, the most in April (34.0 inches).
What is the rainiest month at Mystic Lake?
May, with 4.10 in of precipitation in a normal year; the driest is January with 1.12 in.
What plant hardiness zone is Mystic Lake in?
The USDA's 2023 map puts Mystic Lake in zone 5a in ZIP code 59028, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −17°F (29 years, 1991-2020): zone 5a.
How late can frost come at Mystic Lake?
In half of years the last 32°F night comes after June 5; in one year in ten it comes after June 21. Waiting until June 21 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Nye, MT14 miles from this station, 45.2°F a year
- Silver Gate, MT19 miles from this station, 34.3°F a year
- Cooke City, MT21 miles from this station, 34.2°F a year
- Red Lodge, MT24 miles from this station, 43.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made