Pompeys Pillar (15 mi N), Montana climate: Climate normals at a NOAA weather station
Pompeys Pillar (15 mi N)'s normal year runs from 10°F January nights to 85°F July afternoons, with 14.5 inches of precipitation and 46 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.8°C, January lows of −12°C, July highs of 29°C, 369 mm of precipitation a year.
- NOAA stationPompeys Pillar (15 mi N)
- Station IDUSC00246647
- Location46.20°N 108.00°W
- Elevation3,390 ft (1,033 m)
On October 22, the normal high in Pompeys Pillar (15 mi N) is 55°F and the normal low 28°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Pompeys Pillar (15 mi N).
- Jan 34° 10°
- Feb 37° 12°
- Mar 46° 20°
- Apr 55° 29°
- May 65° 39°
- Jun 75° 48°
- Jul 85° 54°
- Aug 85° 52°
- Sep 73° 42°
- Oct 58° 30°
- Nov 45° 19°
- Dec 36° 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 Pompeys Pillar (15 mi N) each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 10°F. The most precipitation falls in June (2.65 in), the least in December (0.44 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 34°F | 10°F | 21.9°F | 0.51 | 6.7 | 7 | <1 | 29 | 9 h |
| February | 37°F | 12°F | 24.4°F | 0.57 | 9.8 | 8 | <1 | 27 | 10 h 20 min |
| March | 46°F | 20°F | 33.0°F | 0.74 | 7.6 | 7 | <1 | 28 | 11 h 50 min |
| April | 55°F | 29°F | 42.1°F | 1.63 | 4.2 | 9 | <1 | 18 | 13 h 30 min |
| May | 65°F | 39°F | 51.8°F | 2.59 | 1.1 | 11 | <1 | 5 | 15 h |
| June | 75°F | 48°F | 61.3°F | 2.65 | 0.0 | 12 | 2 | <1 | 15 h 50 min |
| July | 85°F | 54°F | 69.7°F | 1.35 | 0.0 | 8 | 14 | <1 | 15 h 30 min |
| August | 85°F | 52°F | 68.8°F | 0.90 | 0.0 | 6 | 12 | <1 | 14 h 10 min |
| September | 73°F | 42°F | 57.8°F | 1.20 | 0.2 | 7 | 3 | 2 | 12 h 40 min |
| October | 58°F | 30°F | 44.1°F | 1.40 | 5.0 | 8 | <1 | 17 | 11 h |
| November | 45°F | 19°F | 32.2°F | 0.54 | 4.4 | 6 | <1 | 25 | 9 h 30 min |
| December | 36°F | 12°F | 23.8°F | 0.44 | 7.1 | 6 | <1 | 30 | 8 h 40 min |
| Year (annual) | 58°F | 31°F | 44.2°F | 14.52 | 46.1 | 95 | 32 | 182 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 1°C | −12°C | −5.6°C | 13 mm | 17 cm |
| February | 3°C | −11°C | −4.2°C | 14 mm | 25 cm |
| March | 8°C | −7°C | 0.6°C | 19 mm | 19 cm |
| April | 13°C | −2°C | 5.6°C | 41 mm | 11 cm |
| May | 18°C | 4°C | 11.0°C | 66 mm | 3 cm |
| June | 24°C | 9°C | 16.3°C | 67 mm | 0 cm |
| July | 29°C | 12°C | 20.9°C | 34 mm | 0 cm |
| August | 30°C | 11°C | 20.4°C | 23 mm | 0 cm |
| September | 23°C | 6°C | 14.3°C | 30 mm | 1 cm |
| October | 14°C | −1°C | 6.7°C | 36 mm | 13 cm |
| November | 7°C | −7°C | 0.1°C | 14 mm | 11 cm |
| December | 2°C | −11°C | −4.6°C | 11 mm | 18 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00246647; 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 Pompeys Pillar (15 mi N)?
Normal highs sit between 65°F and 85°F in June, July and September. Of those, September has the fewest days with rain (7).
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 USC00246647.
When is the last frost at Pompeys Pillar (15 mi N)?
In Pompeys Pillar (15 mi N), the last spring frost (32°F) comes after May 22 in half of years and after June 7 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 221 year in 10 after June 7; 9 in 10 after May 9
- First autumn frost, half of years before
- September 221 year in 10 before September 7; 9 in 10 before October 4
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 10 in half of springs and before October 2 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Pompeys Pillar (15 mi N) in zone 4b in ZIP code 59088, 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 4a: the coldest night of a typical year reaches −25°F (20 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 USC00246647; 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 Pompeys Pillar (15 mi N)?
In a normal year in Pompeys Pillar (15 mi N), 32 days a year reach 90°F (3 of them 100°F or more), 182 nights fall to 32°F or colder and 95 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
- 182a normal year
- Days that stay below freezing
- 41high of 32°F or less
- Days with 0.01 inch of precipitation
- 95a normal year
- Days with 1 inch of snow or more
- 14a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00246647.
How sunny is it at Pompeys Pillar (15 mi N)?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds at Pompeys Pillar (15 mi N), 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 72% | 1.7 |
| February | 74% | 2.6 |
| March | 71% | 3.7 |
| April | 68% | 4.8 |
| May | 71% | 5.8 |
| June | 77% | 6.7 |
| July | 87% | 7.1 |
| August | 85% | 5.9 |
| September | 79% | 4.4 |
| October | 73% | 2.8 |
| November | 71% | 1.8 |
| December | 66% | 1.3 |
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 Pompeys Pillar (15 mi N) record?
A normal year at Pompeys Pillar (15 mi N) brings 7,958 heating degree days, 48% more than the median U.S. place (5,373), and 419 cooling degree days, 54% 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 2,045 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,336 | 0 |
| February | 1,138 | 0 |
| March | 994 | 0 |
| April | 687 | 0 |
| May | 416 | 6 |
| June | 153 | 40 |
| July | 29 | 173 |
| August | 47 | 166 |
| September | 248 | 31 |
| October | 648 | 1 |
| November | 986 | 0 |
| December | 1,277 | 0 |
| Year (annual) | 7,958 | 419 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00246647. 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 Pompeys Pillar (15 mi N) been warmer than normal?
2025 averaged 46.4°F, 2.2°F above the 1991-2020 normal of 44.2°F. 3 of the 3 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 45.8°F | +1.6°F | 15.03 | 46.9 |
| 2024 | 47.3°F | +3.1°F | 17.45 | 18.6 |
| 2025 | 46.4°F | +2.2°F | 20.78 | 58.9 |
Source: observed years: ACIS, station USC00246647. A year counts only with all twelve months complete.
How does Pompeys Pillar (15 mi N)'s climate compare?
Pompeys Pillar (15 mi N) is warmer than 77 of the 141 places with their own NOAA record in Montana, and wetter than 57. Across the 7,247 U.S. stations with normals, its annual mean of 44.2°F is warmer than 16%.
In the Köppen classification computed from these normals, Pompeys Pillar (15 mi N) 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.
Which places near Pompeys Pillar (15 mi N) share this climate record?
Pompeys Pillar 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.
- Pompeys Pillar, MT25 people · 14 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 Pompeys Pillar (15 mi N)'s climate
What is the coldest month at Pompeys Pillar (15 mi N)?
January, with a normal high of 34°F and a normal low of 10°F. The warmest is July (85°F by day, 54°F at night).
Does it snow at Pompeys Pillar (15 mi N)?
Yes: 46 inches in a normal year, falling on 37 days with 0.1 inch or more, the most in February (9.8 inches).
What is the rainiest month at Pompeys Pillar (15 mi N)?
June, with 2.65 in of precipitation in a normal year; the driest is December with 0.44 in.
What plant hardiness zone is Pompeys Pillar (15 mi N) in?
The USDA's 2023 map puts Pompeys Pillar (15 mi N) in zone 4b in ZIP code 59088, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −25°F (20 years, 1991-2020): zone 4a.
How late can frost come at Pompeys Pillar (15 mi N)?
In half of years the last 32°F night comes after May 22; in one year in ten it comes after June 7. Waiting until June 7 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Huntley, MT22 miles from this station, 46.1°F a year
- Melstone, MT29 miles from this station, 47.2°F a year
- Roundup, MT30 miles from this station, 46.5°F a year
- Hardin, MT37 miles from this station, 47.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made