Sweetgrass, Montana climate: Climate normals at a NOAA weather station
Sweetgrass's normal year runs from 10°F January nights to 82°F July afternoons. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.4°C, January lows of −12°C, July highs of 28°C.
- NOAA stationSweetgrass
- Station IDUSC00248093
- Location49.00°N 111.96°W
- Elevation3,510 ft (1,070 m)
On October 22, the normal high in Sweetgrass is 54°F and the normal low 30°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Sweetgrass.
- Jan 32° 10°
- Feb 35° 12°
- Mar 44° 21°
- Apr 55° 30°
- May 66° 39°
- Jun 73° 47°
- Jul 82° 53°
- Aug 82° 51°
- Sep 72° 42°
- Oct 57° 32°
- Nov 43° 21°
- Dec 33° 12°
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 Sweetgrass each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 10°F.
| Month | High | Low | Mean | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|
| January | 32°F | 10°F | 21.3°F | – | <1 | 29 | 8 h 40 min |
| February | 35°F | 12°F | 23.7°F | – | <1 | 25 | 10 h 10 min |
| March | 44°F | 21°F | 32.3°F | – | <1 | 26 | 11 h 50 min |
| April | 55°F | 30°F | 42.0°F | – | <1 | 18 | 13 h 40 min |
| May | 66°F | 39°F | 52.5°F | – | <1 | 6 | 15 h 10 min |
| June | 73°F | 47°F | 60.0°F | – | 1 | <1 | 16 h 10 min |
| July | 82°F | 53°F | 67.7°F | – | 7 | <1 | 15 h 50 min |
| August | 82°F | 51°F | 66.6°F | – | 7 | <1 | 14 h 30 min |
| September | 72°F | 42°F | 57.1°F | – | 1 | 4 | 12 h 40 min |
| October | 57°F | 32°F | 44.5°F | – | <1 | 16 | 10 h 50 min |
| November | 43°F | 21°F | 31.8°F | – | <1 | 25 | 9 h 10 min |
| December | 33°F | 12°F | 22.1°F | – | <1 | 29 | 8 h 20 min |
| Year (annual) | 56°F | 31°F | 43.5°F | – | 16 | 179 |
The same normals in °C and millimetres
| Month | High | Low | Mean |
|---|---|---|---|
| January | 0°C | −12°C | −5.9°C |
| February | 2°C | −11°C | −4.6°C |
| March | 7°C | −6°C | 0.2°C |
| April | 13°C | −1°C | 5.6°C |
| May | 19°C | 4°C | 11.4°C |
| June | 23°C | 8°C | 15.6°C |
| July | 28°C | 12°C | 19.8°C |
| August | 28°C | 11°C | 19.2°C |
| September | 22°C | 6°C | 13.9°C |
| October | 14°C | 0°C | 6.9°C |
| November | 6°C | −6°C | −0.1°C |
| December | 0°C | −11°C | −5.5°C |
NOAA publishes no 1991-2020 snowfall normal for this station, and no record within 25 miles keeps one, so snow is left out here rather than estimated.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00248093; 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 Sweetgrass?
Normal highs sit between 65°F and 85°F in May, June, July, 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 USC00248093.
When is the last frost at Sweetgrass?
In Sweetgrass, the last spring frost (32°F) comes after May 15 in half of years and after May 28 in one year in ten; the first autumn frost comes before September 25 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 151 year in 10 after May 28; 9 in 10 after May 3
- First autumn frost, half of years before
- September 251 year in 10 before September 11; 9 in 10 before October 8
NOAA puts the median frost-free season at 132 days, and the season without a hard freeze (28°F) at 152 days.
A hard freeze (28°F) comes after May 4 in half of springs and before October 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sweetgrass in zone 4a in ZIP code 59482, 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 USC00248093; 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 at Sweetgrass?
In a normal year in Sweetgrass, 16 days a year reach 90°F (1 of them 100°F or more) and 179 nights fall to 32°F or colder.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 179a normal year
- Days that stay below freezing
- 45high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00248093.
How sunny is it at Sweetgrass?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds at Sweetgrass, 3.9 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 1.3 |
| February | 69% | 2.3 |
| March | 70% | 3.5 |
| April | 72% | 4.9 |
| May | 73% | 5.9 |
| June | 78% | 6.6 |
| July | 87% | 7.1 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 73% | 2.6 |
| November | 67% | 1.5 |
| December | 62% | 1.0 |
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 Sweetgrass record?
A normal year at Sweetgrass brings 8,119 heating degree days, 51% more than the median U.S. place (5,373), and 307 cooling degree days, 66% 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 1,848 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,355 | 0 |
| February | 1,156 | 0 |
| March | 1,012 | 0 |
| April | 689 | 0 |
| May | 393 | 5 |
| June | 175 | 25 |
| July | 53 | 136 |
| August | 68 | 117 |
| September | 258 | 21 |
| October | 636 | 2 |
| November | 996 | 0 |
| December | 1,330 | 0 |
| Year (annual) | 8,119 | 307 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00248093. 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 Sweetgrass's climate compare?
Sweetgrass is warmer than 56 of the 141 places with their own NOAA record in Montana. Across the 7,247 U.S. stations with normals, its annual mean of 43.5°F is warmer than 14%.
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers.
Which places near Sweetgrass share this climate record?
4 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.
- Glacier Colony, MT390 people · 16 mi SW
- Hillside Colony, MT267 people · 5 mi W
- Rimrock Colony, MT157 people · 9 mi SW
- Sweet Grass, MT64 people · 0 mi S
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 Sweetgrass's climate
What is the coldest month at Sweetgrass?
January, with a normal high of 32°F and a normal low of 10°F. The warmest is July (82°F by day, 53°F at night).
What plant hardiness zone is Sweetgrass in?
The USDA's 2023 map puts Sweetgrass in zone 4a in ZIP code 59482, the nearest ZIP area.
How late can frost come at Sweetgrass?
In half of years the last 32°F night comes after May 15; in one year in ten it comes after May 28. Waiting until May 28 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Sunburst, MT13 miles from this station, 43.3°F a year
- Goldbutte (7 mi N), MT25 miles from this station, 41.7°F a year
- Dunkirk (19 mi NNE), MT29 miles from this station, 41.0°F a year
- Cut Bank, MT33 miles from this station, 41.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made