Circle, Montana climate: Normal weather by month, frost dates and records
Circle's normal year runs from 8°F January nights to 87°F July afternoons, with 14.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.3°C, January lows of −13°C, July highs of 31°C, 367 mm of precipitation a year.
- NOAA stationCircle
- Station IDUSC00241758
- Location47.41°N 105.60°W
- Elevation2,480 ft (756 m)
- Population586
On October 22, the normal high in Circle is 55°F and the normal low 31°F, and the chance of measurable rain or snow is 13%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Circle.
- Jan 29° 8°
- Feb 33° 12°
- Mar 46° 22°
- Apr 58° 32°
- May 68° 42°
- Jun 78° 51°
- Jul 87° 57°
- Aug 87° 55°
- Sep 76° 45°
- Oct 59° 33°
- Nov 43° 21°
- Dec 32° 11°
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 Circle each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 8°F. The most precipitation falls in June (2.64 in), the least in November (0.36 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 29°F | 8°F | 18.1°F | 0.40 | 5 | <1 | 31 | 8 h 50 min |
| February | 33°F | 12°F | 22.1°F | 0.37 | 4 | <1 | 27 | 10 h 10 min |
| March | 46°F | 22°F | 33.6°F | 0.49 | 4 | <1 | 27 | 11 h 50 min |
| April | 58°F | 32°F | 44.9°F | 1.38 | 5 | <1 | 17 | 13 h 30 min |
| May | 68°F | 42°F | 55.0°F | 2.55 | 7 | <1 | 6 | 15 h |
| June | 78°F | 51°F | 64.3°F | 2.64 | 9 | 3 | <1 | 16 h |
| July | 87°F | 57°F | 72.1°F | 2.14 | 7 | 13 | <1 | 15 h 40 min |
| August | 87°F | 55°F | 71.1°F | 1.40 | 4 | 13 | <1 | 14 h 20 min |
| September | 76°F | 45°F | 60.3°F | 1.33 | 5 | 4 | 3 | 12 h 40 min |
| October | 59°F | 33°F | 46.0°F | 0.93 | 4 | <1 | 16 | 11 h |
| November | 43°F | 21°F | 32.0°F | 0.36 | 4 | <1 | 26 | 9 h 20 min |
| December | 32°F | 11°F | 21.3°F | 0.46 | 4 | <1 | 31 | 8 h 30 min |
| Year (annual) | 58°F | 32°F | 45.1°F | 14.45 | 62 | 32 | 183 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −13°C | −7.7°C | 10 mm |
| February | 0°C | −11°C | −5.5°C | 9 mm |
| March | 8°C | −6°C | 0.9°C | 12 mm |
| April | 15°C | 0°C | 7.2°C | 35 mm |
| May | 20°C | 5°C | 12.8°C | 65 mm |
| June | 25°C | 11°C | 17.9°C | 67 mm |
| July | 31°C | 14°C | 22.3°C | 54 mm |
| August | 30°C | 13°C | 21.7°C | 36 mm |
| September | 24°C | 7°C | 15.7°C | 34 mm |
| October | 15°C | 1°C | 7.8°C | 24 mm |
| November | 6°C | −6°C | 0.0°C | 9 mm |
| December | 0°C | −12°C | −5.9°C | 12 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 USC00241758; 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 Circle?
Normal highs sit between 65°F and 85°F in May, June and September. Of those, September has the fewest days with rain (5).
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 USC00241758.
When is the last frost in Circle?
In Circle, the last spring frost (32°F) comes after May 17 in half of years and after May 31 in one year in ten; the first autumn frost comes before September 22 in half of years and before September 7 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 171 year in 10 after May 31; 9 in 10 after May 4
- First autumn frost, half of years before
- September 221 year in 10 before September 7; 9 in 10 before October 6
NOAA puts the median frost-free season at 126 days, and the season without a hard freeze (28°F) at 146 days.
A hard freeze (28°F) comes after May 6 in half of springs and before October 1 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Circle in zone 4a in ZIP code 59215, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Circle's NOAA station is in zone 3b: the coldest night of a typical year reaches −30°F (29 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00241758; 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 Circle?
In a normal year in Circle, 32 days a year reach 90°F (3 of them 100°F or more), 183 nights fall to 32°F or colder and 62 days bring measurable precipitation.
- Days at 90°F or more
- 32a normal year
- Days at 100°F or more
- 3a normal year
- Nights at 32°F or colder
- 183a normal year
- Days that stay below freezing
- 58high of 32°F or less
- Days with 0.01 inch of precipitation
- 62a normal year
The highest temperature in this station's record (since 1963) is 112°F, on July 12, 2026; the lowest is −46°F, on December 21, 1989.
The wettest calendar year on that record is 2010, with 22.40 in; the snowiest season is 1978–79, with 66.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00241758; records: ACIS (NOAA Regional Climate Centers), station USC00241758. Records use complete months only; a month missing more than three days is left out.
How sunny is Circle?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Circle, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 77% | 1.7 |
| February | 79% | 2.7 |
| March | 75% | 3.8 |
| April | 72% | 4.9 |
| May | 74% | 5.9 |
| June | 79% | 6.7 |
| July | 87% | 7.0 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 74% | 2.7 |
| November | 72% | 1.7 |
| December | 70% | 1.2 |
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 Circle need?
A normal year in Circle brings 7,832 heating degree days, 46% more than the median U.S. place (5,373), and 601 cooling degree days, 34% 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 2,441 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,452 | 0 |
| February | 1,203 | 0 |
| March | 975 | 0 |
| April | 604 | 1 |
| May | 323 | 13 |
| June | 97 | 76 |
| July | 17 | 237 |
| August | 29 | 218 |
| September | 193 | 54 |
| October | 594 | 3 |
| November | 990 | 0 |
| December | 1,356 | 0 |
| Year (annual) | 7,832 | 601 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00241758. 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 Circle been warmer than normal lately?
2025 averaged 46.3°F, 1.2°F above the 1991-2020 normal of 45.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 46.8°F | +1.7°F | 8.76 |
| 2022 | 43.7°F | −1.4°F | 12.55 |
| 2023 | 46.3°F | +1.2°F | 15.77 |
| 2024 | 47.1°F | +2.0°F | 13.22 |
| 2025 | 46.3°F | +1.2°F | 18.30 |
Over 50 complete years from 1965 to 2025, the station's annual mean temperature rose at a fitted 4.5°F per century (+0.25°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00241758; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Circle's climate compare?
Circle is warmer than 93 of the other 140 places with their own NOAA record in Montana, and wetter than 56. Across the 7,247 U.S. stations with normals, its annual mean of 45.1°F is warmer than 20%.
In the Köppen classification computed from these normals, Circle 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 Circle's climate
What is the coldest month in Circle?
January, with a normal high of 29°F and a normal low of 8°F. The warmest is July (87°F by day, 57°F at night).
What is the rainiest month in Circle?
June, with 2.64 in of precipitation in a normal year; the driest is November with 0.36 in.
What plant hardiness zone is Circle in?
The USDA's 2023 map puts Circle in zone 4a in ZIP code 59215, the nearest ZIP area. By the same method at Circle's NOAA station, the coldest night of a typical year reaches −30°F (29 years, 1991-2020): zone 3b.
How late can frost come in Circle?
In half of years the last 32°F night comes after May 17; in one year in ten it comes after May 31. Waiting until May 31 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Brockway, MT14 miles from this station, 44.0°F a year
- Vida, MT34 miles from this station, 43.5°F a year
- Terry, MT45 miles from this station, 45.3°F a year
- Glendive, MT47 miles from this station, 46.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made