Chinook (35 mi SE), Montana climate: Climate normals at a NOAA weather station
Chinook (35 mi SE)'s normal year runs from 12°F January nights to 80°F July afternoons, with 13.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.2°C, January lows of −11°C, July highs of 27°C, 340 mm of precipitation a year.
- NOAA stationChinook (35 mi SE)
- Station IDUSC00241730
- Location48.17°N 109.01°W
- Elevation3,360 ft (1,024 m)
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Chinook (35 mi SE).
- Jan 34° 12°
- Feb 35° 13°
- Mar 44° 20°
- Apr 55° 29°
- May 63° 37°
- Jun 71° 47°
- Jul 80° 52°
- Aug 80° 50°
- Sep 69° 42°
- Oct 57° 32°
- Nov 43° 22°
- Dec 35° 14°
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 Chinook (35 mi SE) each month?
July is the warmest month, with normal highs of 80°F; January the coldest, with normal lows of 12°F. The most precipitation falls in June (3.00 in), the least in January (0.34 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 34°F | 12°F | 23.1°F | 0.34 | – | <1 | 29 | 8 h 50 min |
| February | 35°F | 13°F | 24.1°F | 0.40 | – | <1 | 27 | 10 h 10 min |
| March | 44°F | 20°F | 32.3°F | 0.57 | – | <1 | 28 | 11 h 50 min |
| April | 55°F | 29°F | 42.0°F | 1.06 | – | <1 | 20 | 13 h 40 min |
| May | 63°F | 37°F | 50.0°F | 2.15 | – | <1 | 11 | 15 h 10 min |
| June | 71°F | 47°F | 58.8°F | 3.00 | – | 1 | 1 | 16 h |
| July | 80°F | 52°F | 66.3°F | 1.72 | – | 7 | <1 | 15 h 40 min |
| August | 80°F | 50°F | 65.0°F | 1.13 | – | 4 | <1 | 14 h 20 min |
| September | 69°F | 42°F | 55.1°F | 1.03 | – | 1 | 3 | 12 h 40 min |
| October | 57°F | 32°F | 44.1°F | 1.06 | – | <1 | 18 | 11 h |
| November | 43°F | 22°F | 32.5°F | 0.51 | – | <1 | 25 | 9 h 20 min |
| December | 35°F | 14°F | 24.6°F | 0.41 | – | <1 | 29 | 8 h 20 min |
| Year (annual) | 56°F | 31°F | 43.2°F | 13.38 | – | 12 | 188 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 1°C | −11°C | −4.9°C | 9 mm |
| February | 2°C | −11°C | −4.4°C | 10 mm |
| March | 7°C | −6°C | 0.2°C | 14 mm |
| April | 13°C | −1°C | 5.6°C | 27 mm |
| May | 17°C | 3°C | 10.0°C | 55 mm |
| June | 22°C | 8°C | 14.9°C | 76 mm |
| July | 27°C | 11°C | 19.1°C | 44 mm |
| August | 27°C | 10°C | 18.3°C | 29 mm |
| September | 20°C | 5°C | 12.8°C | 26 mm |
| October | 14°C | 0°C | 6.7°C | 27 mm |
| November | 6°C | −6°C | 0.3°C | 13 mm |
| December | 2°C | −10°C | −4.1°C | 10 mm |
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 USC00241730; 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 Chinook (35 mi SE)?
Normal highs sit between 65°F and 85°F in 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 USC00241730.
When is the last frost at Chinook (35 mi SE)?
In Chinook (35 mi SE), the last spring frost (32°F) comes after May 23 in half of years and after June 3 in one year in ten; the first autumn frost comes before September 23 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 231 year in 10 after June 3; 9 in 10 after May 11
- First autumn frost, half of years before
- September 231 year in 10 before September 11; 9 in 10 before October 3
NOAA puts the median frost-free season at 121 days, and the season without a hard freeze (28°F) at 142 days.
A hard freeze (28°F) comes after May 11 in half of springs and before September 30 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Chinook (35 mi SE) in zone 4b in ZIP code 59527, 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 USC00241730; 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 Chinook (35 mi SE)?
In a normal year in Chinook (35 mi SE), 12 days a year reach 90°F and 188 nights fall to 32°F or colder.
- Days at 90°F or more
- 12a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 188a normal year
- Days that stay below freezing
- 45high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00241730.
How sunny is it at Chinook (35 mi SE)?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds at Chinook (35 mi SE), 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (69%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 75% | 1.5 |
| February | 78% | 2.6 |
| March | 75% | 3.8 |
| April | 73% | 4.9 |
| May | 74% | 5.9 |
| June | 78% | 6.6 |
| July | 87% | 7.0 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 74% | 2.7 |
| November | 71% | 1.6 |
| December | 69% | 1.1 |
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 Chinook (35 mi SE) record?
A normal year at Chinook (35 mi SE) brings 8,144 heating degree days, 52% more than the median U.S. place (5,373), and 219 cooling degree days, 76% fewer than the median (908). Nine months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,634 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,300 | 0 |
| February | 1,144 | 0 |
| March | 1,014 | 0 |
| April | 690 | 0 |
| May | 466 | 3 |
| June | 203 | 17 |
| July | 61 | 101 |
| August | 83 | 84 |
| September | 311 | 14 |
| October | 647 | 1 |
| November | 975 | 0 |
| December | 1,251 | 0 |
| Year (annual) | 8,144 | 219 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00241730. 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 Chinook (35 mi SE)'s climate compare?
Chinook (35 mi SE) is warmer than 52 of the 141 places with their own NOAA record in Montana, and wetter than 40. Across the 7,247 U.S. stations with normals, its annual mean of 43.2°F is warmer than 13%.
In the Köppen classification computed from these normals, Chinook (35 mi SE) 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 Chinook (35 mi SE)'s climate
What is the coldest month at Chinook (35 mi SE)?
January, with a normal high of 34°F and a normal low of 12°F. The warmest is July (80°F by day, 52°F at night).
What is the rainiest month at Chinook (35 mi SE)?
June, with 3.00 in of precipitation in a normal year; the driest is January with 0.34 in.
What plant hardiness zone is Chinook (35 mi SE) in?
The USDA's 2023 map puts Chinook (35 mi SE) in zone 4b in ZIP code 59527, the nearest ZIP area.
How late can frost come at Chinook (35 mi SE)?
In half of years the last 32°F night comes after May 23; in one year in ten it comes after June 3. Waiting until June 3 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Fort Belknap (2 mi SW), MT22 miles from this station, 42.6°F a year
- Harlem, MT27 miles from this station, 43.5°F a year
- Zortman, MT29 miles from this station, 43.2°F a year
- Chinook, MT30 miles from this station, 42.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made