Holter Dam, Montana climate: Climate normals at a NOAA weather station
Holter Dam's normal year runs from 20°F January nights to 85°F July afternoons, with 13.8 inches of precipitation and 28 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.2°C, January lows of −7°C, July highs of 30°C, 350 mm of precipitation a year.
- NOAA stationHolter Dam
- Station IDUSC00244241
- Location46.99°N 112.01°W
- Elevation3,487 ft (1,063 m)
On October 23, the normal high in Holter Dam is 56°F and the normal low 34°F, and the chance of measurable rain or snow is 20%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Holter Dam.
- Jan 37° 20°
- Feb 40° 20°
- Mar 49° 26°
- Apr 57° 32°
- May 67° 39°
- Jun 75° 46°
- Jul 85° 51°
- Aug 85° 50°
- Sep 74° 44°
- Oct 59° 36°
- Nov 45° 28°
- Dec 37° 22°
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 Holter Dam each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 20°F. The most precipitation falls in June (2.87 in), the least in January (0.32 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 37°F | 20°F | 28.3°F | 0.32 | 6.9 | 6 | <1 | 23 | 8 h 50 min |
| February | 40°F | 20°F | 29.9°F | 0.36 | 5.4 | 6 | <1 | 22 | 10 h 20 min |
| March | 49°F | 26°F | 37.4°F | 0.61 | 2.7 | 6 | <1 | 21 | 11 h 50 min |
| April | 57°F | 32°F | 44.6°F | 1.54 | 2.2 | 9 | <1 | 15 | 13 h 30 min |
| May | 67°F | 39°F | 52.9°F | 2.56 | 0.1 | 11 | <1 | 5 | 15 h |
| June | 75°F | 46°F | 60.6°F | 2.87 | 0.2 | 10 | 2 | <1 | 15 h 50 min |
| July | 85°F | 51°F | 68.3°F | 1.03 | 0.0 | 6 | 13 | <1 | 15 h 30 min |
| August | 85°F | 50°F | 67.3°F | 1.16 | 0.0 | 7 | 12 | <1 | 14 h 20 min |
| September | 74°F | 44°F | 58.8°F | 1.30 | 0.0 | 7 | 2 | 2 | 12 h 40 min |
| October | 59°F | 36°F | 47.8°F | 1.04 | 0.9 | 7 | <1 | 10 | 11 h |
| November | 45°F | 28°F | 36.7°F | 0.51 | 3.4 | 5 | <1 | 17 | 9 h 20 min |
| December | 37°F | 22°F | 29.1°F | 0.46 | 6.2 | 5 | <1 | 23 | 8 h 30 min |
| Year (annual) | 59°F | 35°F | 46.8°F | 13.76 | 28.0 | 85 | 29 | 136 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −7°C | −2.1°C | 8 mm | 18 cm |
| February | 4°C | −7°C | −1.2°C | 9 mm | 14 cm |
| March | 9°C | −3°C | 3.0°C | 15 mm | 7 cm |
| April | 14°C | 0°C | 7.0°C | 39 mm | 6 cm |
| May | 19°C | 4°C | 11.6°C | 65 mm | 0 cm |
| June | 24°C | 8°C | 15.9°C | 73 mm | 1 cm |
| July | 30°C | 11°C | 20.2°C | 26 mm | 0 cm |
| August | 29°C | 10°C | 19.6°C | 29 mm | 0 cm |
| September | 23°C | 6°C | 14.9°C | 33 mm | 0 cm |
| October | 15°C | 2°C | 8.8°C | 26 mm | 2 cm |
| November | 7°C | −2°C | 2.6°C | 13 mm | 9 cm |
| December | 3°C | −6°C | −1.6°C | 12 mm | 16 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244241; 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 Holter Dam?
Normal highs sit between 65°F and 85°F in May, June, August 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 USC00244241.
When is the last frost at Holter Dam?
In Holter Dam, the last spring frost (32°F) comes after May 19 in half of years and after June 8 in one year in ten; the first autumn frost comes before September 24 in half of years and before September 6 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 191 year in 10 after June 8; 9 in 10 after May 6
- First autumn frost, half of years before
- September 241 year in 10 before September 6; 9 in 10 before October 7
NOAA puts the median frost-free season at 124 days, and the season without a hard freeze (28°F) at 149 days.
A hard freeze (28°F) comes after May 6 in half of springs and before October 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Holter Dam in zone 4b in ZIP code 59648, 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 4b: the coldest night of a typical year reaches −21°F (25 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 USC00244241; 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 Holter Dam?
In a normal year in Holter Dam, 29 days a year reach 90°F (1 of them 100°F or more), 136 nights fall to 32°F or colder and 85 days bring measurable precipitation.
- Days at 90°F or more
- 29a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 136a normal year
- Days that stay below freezing
- 27high of 32°F or less
- Days with 0.01 inch of precipitation
- 85a normal year
- Days with 1 inch of snow or more
- 10a normal year
The highest temperature in this station's record (since 1903) is 108°F, on July 30, 1936; the lowest is −44°F, on January 10, 1909.
The wettest calendar year on that record is 1993, with 19.80 in; the snowiest season is 1941–42, with 90.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00244241; records: ACIS (NOAA Regional Climate Centers), station USC00244241. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Holter Dam?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds at Holter Dam, 4.0 kWh per square metre a day. July is the sunniest month (86%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 1.5 |
| February | 70% | 2.5 |
| March | 69% | 3.7 |
| April | 68% | 4.8 |
| May | 69% | 5.7 |
| June | 74% | 6.5 |
| July | 86% | 7.3 |
| August | 84% | 6.0 |
| September | 79% | 4.5 |
| October | 70% | 2.8 |
| November | 64% | 1.6 |
| December | 61% | 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 many heating and cooling degree days does Holter Dam record?
A normal year at Holter Dam brings 6,912 heating degree days, 29% 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 2,005 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,136 | 0 |
| February | 984 | 0 |
| March | 856 | 0 |
| April | 612 | 0 |
| May | 377 | 3 |
| June | 159 | 26 |
| July | 34 | 135 |
| August | 47 | 117 |
| September | 209 | 23 |
| October | 538 | 3 |
| November | 849 | 0 |
| December | 1,111 | 0 |
| Year (annual) | 6,912 | 307 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244241. 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 Holter Dam been warmer than normal?
2022 averaged 46.3°F, 0.5°F below the 1991-2020 normal of 46.8°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 46.3°F | −0.5°F | 13.19 | 69.4 |
Over 95 complete years from 1904 to 2025, the station's annual mean temperature rose at a fitted 1.9°F per century (+0.11°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00244241; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Holter Dam's climate compare?
Holter Dam is warmer than 126 of the 141 places with their own NOAA record in Montana, and wetter than 48. Across the 7,247 U.S. stations with normals, its annual mean of 46.8°F is warmer than 27%.
In the Köppen classification computed from these normals, Holter Dam 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 Holter Dam share this climate record?
2 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.
- Craig, MT47 people · 6 mi N
- Wolf Creek, MT18 people · 3 mi W
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 Holter Dam's climate
What is the coldest month at Holter Dam?
January, with a normal high of 37°F and a normal low of 20°F. The warmest is July (85°F by day, 51°F at night).
Does it snow at Holter Dam?
Yes: 28 inches in a normal year, falling on 17 days with 0.1 inch or more, the most in January (6.9 inches).
What is the rainiest month at Holter Dam?
June, with 2.87 in of precipitation in a normal year; the driest is January with 0.32 in.
What plant hardiness zone is Holter Dam in?
The USDA's 2023 map puts Holter Dam in zone 4b in ZIP code 59648, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −21°F (25 years, 1991-2020): zone 4b.
How late can frost come at Holter Dam?
In half of years the last 32°F night comes after May 19; in one year in ten it comes after June 8. Waiting until June 8 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Adel, MT16 miles from this station, 41.5°F a year
- Rogers Pass (9 mi NNE), MT19 miles from this station, 43.9°F a year
- Cascade, MT21 miles from this station, 47.0°F a year
- Austin (1 mi W), MT27 miles from this station, 40.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made