Gibson Dam, Montana climate: Climate normals at a NOAA weather station
Gibson Dam's normal year runs from 13°F December nights to 79°F July afternoons, with 16.6 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 4.7°C, December lows of −10°C, July highs of 26°C, 420 mm of precipitation a year.
- NOAA stationGibson Dam
- Station IDUSC00243489
- Location47.60°N 112.75°W
- Elevation4,590 ft (1,399 m)
On October 23, the normal high in Gibson Dam is 51°F and the normal low 26°F, and the chance of measurable rain or snow is 17%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Gibson Dam.
- Jan 36° 12°
- Feb 36° 12°
- Mar 43° 19°
- Apr 50° 25°
- May 59° 33°
- Jun 67° 39°
- Jul 79° 45°
- Aug 78° 43°
- Sep 68° 36°
- Oct 54° 29°
- Nov 42° 20°
- Dec 35° 13°
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 Gibson Dam each month?
July is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 13°F. The most precipitation falls in June (3.13 in), the least in January (0.67 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 36°F | 12°F | 24.0°F | 0.67 | 5 | <1 | 28 | 8 h 50 min |
| February | 36°F | 12°F | 24.1°F | 0.92 | 6 | <1 | 27 | 10 h 10 min |
| March | 43°F | 19°F | 30.5°F | 0.82 | 7 | <1 | 28 | 11 h 50 min |
| April | 50°F | 25°F | 37.6°F | 1.63 | 8 | <1 | 25 | 13 h 30 min |
| May | 59°F | 33°F | 45.9°F | 2.93 | 10 | <1 | 13 | 15 h 10 min |
| June | 67°F | 39°F | 53.3°F | 3.13 | 11 | <1 | 2 | 16 h |
| July | 79°F | 45°F | 61.6°F | 1.14 | 6 | 3 | <1 | 15 h 40 min |
| August | 78°F | 43°F | 60.4°F | 1.33 | 6 | 2 | 1 | 14 h 20 min |
| September | 68°F | 36°F | 51.9°F | 1.31 | 7 | <1 | 6 | 12 h 40 min |
| October | 54°F | 29°F | 41.2°F | 1.12 | 5 | <1 | 20 | 11 h |
| November | 42°F | 20°F | 31.2°F | 0.78 | 5 | <1 | 25 | 9 h 20 min |
| December | 35°F | 13°F | 23.9°F | 0.77 | 5 | <1 | 29 | 8 h 30 min |
| Year (annual) | 54°F | 27°F | 40.5°F | 16.55 | 80 | 5 | 204 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 2°C | −11°C | −4.4°C | 17 mm |
| February | 2°C | −11°C | −4.4°C | 23 mm |
| March | 6°C | −7°C | −0.8°C | 21 mm |
| April | 10°C | −4°C | 3.1°C | 41 mm |
| May | 15°C | 0°C | 7.7°C | 74 mm |
| June | 20°C | 4°C | 11.8°C | 80 mm |
| July | 26°C | 7°C | 16.4°C | 29 mm |
| August | 26°C | 6°C | 15.8°C | 34 mm |
| September | 20°C | 2°C | 11.1°C | 33 mm |
| October | 12°C | −2°C | 5.1°C | 28 mm |
| November | 6°C | −6°C | −0.4°C | 20 mm |
| December | 1°C | −10°C | −4.5°C | 20 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 USC00243489; 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 Gibson Dam?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August has the fewest days with rain (6).
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 USC00243489.
When is the last frost at Gibson Dam?
In Gibson Dam, the last spring frost (32°F) comes after June 12 in half of years and after July 5 in one year in ten; the first autumn frost comes before September 8 in half of years and before August 23 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
- June 121 year in 10 after July 5; 9 in 10 after May 25
- First autumn frost, half of years before
- September 81 year in 10 before August 23; 9 in 10 before September 24
NOAA puts the median frost-free season at 88 days, and the season without a hard freeze (28°F) at 127 days.
A hard freeze (28°F) comes after May 19 in half of springs and before September 24 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Gibson Dam in zone 4b in ZIP code 59410, 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 −23°F (16 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 USC00243489; 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 Gibson Dam?
In a normal year in Gibson Dam, 5 days a year reach 90°F, 204 nights fall to 32°F or colder and 80 days bring measurable precipitation.
- Days at 90°F or more
- 5a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 204a normal year
- Days that stay below freezing
- 41high of 32°F or less
- Days with 0.01 inch of precipitation
- 80a normal year
The highest temperature in this station's record (since 1911) is 106°F, on July 24, 1929; the lowest is −49°F, on February 15, 1936.
The wettest calendar year on that record is 1916, with 29.40 in; the snowiest season is 1953–54, with 131.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00243489; records: ACIS (NOAA Regional Climate Centers), station USC00243489. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Gibson Dam?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds at Gibson Dam, 3.9 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (60%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 64% | 1.4 |
| February | 69% | 2.4 |
| March | 66% | 3.5 |
| April | 66% | 4.6 |
| May | 67% | 5.6 |
| June | 73% | 6.4 |
| July | 87% | 7.3 |
| August | 83% | 5.9 |
| September | 77% | 4.3 |
| October | 69% | 2.6 |
| November | 61% | 1.5 |
| December | 60% | 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 Gibson Dam record?
A normal year at Gibson Dam brings 8,977 heating degree days, 67% more than the median U.S. place (5,373), and 56 cooling degree days, 94% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,018 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,271 | 0 |
| February | 1,145 | 0 |
| March | 1,070 | 0 |
| April | 822 | 0 |
| May | 592 | 0 |
| June | 353 | 2 |
| July | 138 | 32 |
| August | 165 | 21 |
| September | 394 | 1 |
| October | 738 | 0 |
| November | 1,016 | 0 |
| December | 1,274 | 0 |
| Year (annual) | 8,977 | 56 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00243489. 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 Gibson Dam been warmer than normal?
2021 averaged 41.9°F, 1.4°F above the 1991-2020 normal of 40.5°F.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 41.9°F | +1.4°F | – |
Over 66 complete years from 1914 to 2021, the station's annual mean temperature rose at a fitted 2.9°F per century (+0.16°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00243489; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Gibson Dam's climate compare?
Gibson Dam is warmer than 19 of the 141 places with their own NOAA record in Montana, and wetter than 100. Across the 7,247 U.S. stations with normals, its annual mean of 40.5°F is warmer than 6%.
In the Köppen classification computed from these normals, Gibson Dam is Dfb: continental, no dry season, warm summer. 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 Gibson Dam's climate
What is the coldest month at Gibson Dam?
December, with a normal high of 35°F and a normal low of 13°F. The warmest is July (79°F by day, 45°F at night).
What is the rainiest month at Gibson Dam?
June, with 3.13 in of precipitation in a normal year; the driest is January with 0.67 in.
What plant hardiness zone is Gibson Dam in?
The USDA's 2023 map puts Gibson Dam in zone 4b in ZIP code 59410, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −23°F (16 years, 1991-2020): zone 4b.
How late can frost come at Gibson Dam?
In half of years the last 32°F night comes after June 12; in one year in ten it comes after July 5. Waiting until July 5 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Augusta, MT18 miles from this station, 45.4°F a year
- Choteau, MT30 miles from this station, 43.8°F a year
- Bynum, MT31 miles from this station, 43.5°F a year
- Blackleaf, MT32 miles from this station, 41.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made