Yellowtail Dam, Montana climate: Climate normals at a NOAA weather station
Yellowtail Dam's normal year runs from 20°F January nights to 89°F July afternoons, with 16.7 inches of precipitation and 44 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.7°C, January lows of −7°C, July highs of 32°C, 423 mm of precipitation a year.
- NOAA stationYellowtail Dam
- Station IDUSC00249240
- Location45.31°N 107.94°W
- Elevation3,305 ft (1,007 m)
On October 23, the normal high in Yellowtail Dam is 57°F and the normal low 35°F, and the chance of measurable rain or snow is 18%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Yellowtail Dam.
- Jan 39° 20°
- Feb 40° 21°
- Mar 50° 28°
- Apr 58° 36°
- May 68° 44°
- Jun 78° 53°
- Jul 89° 59°
- Aug 87° 57°
- Sep 76° 49°
- Oct 61° 38°
- Nov 48° 28°
- Dec 39° 21°
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 Yellowtail Dam each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 20°F. The most precipitation falls in May (2.62 in), the least in January (0.72 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 39°F | 20°F | 29.0°F | 0.72 | 8.8 | 5 | <1 | 24 | 9 h 10 min |
| February | 40°F | 21°F | 30.5°F | 0.83 | 7.4 | 5 | <1 | 21 | 10 h 20 min |
| March | 50°F | 28°F | 39.1°F | 1.21 | 8.4 | 6 | <1 | 19 | 11 h 50 min |
| April | 58°F | 36°F | 46.8°F | 1.95 | 3.0 | 8 | <1 | 9 | 13 h 30 min |
| May | 68°F | 44°F | 55.9°F | 2.62 | 0.2 | 8 | 1 | 2 | 14 h 50 min |
| June | 78°F | 53°F | 65.6°F | 2.27 | 0.0 | 7 | 5 | <1 | 15 h 40 min |
| July | 89°F | 59°F | 74.0°F | 1.15 | 0.0 | 5 | 18 | <1 | 15 h 20 min |
| August | 87°F | 57°F | 72.3°F | 0.78 | 0.0 | 4 | 17 | <1 | 14 h 10 min |
| September | 76°F | 49°F | 62.3°F | 1.67 | 0.0 | 5 | 5 | 1 | 12 h 40 min |
| October | 61°F | 38°F | 49.3°F | 1.98 | 3.0 | 6 | <1 | 7 | 11 h |
| November | 48°F | 28°F | 37.8°F | 0.77 | 5.8 | 4 | <1 | 19 | 9 h 30 min |
| December | 39°F | 21°F | 30.3°F | 0.72 | 7.3 | 5 | <1 | 24 | 8 h 50 min |
| Year (annual) | 61°F | 38°F | 49.4°F | 16.67 | 43.9 | 66 | 45 | 126 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −7°C | −1.7°C | 18 mm | 22 cm |
| February | 4°C | −6°C | −0.8°C | 21 mm | 19 cm |
| March | 10°C | −2°C | 3.9°C | 31 mm | 21 cm |
| April | 14°C | 2°C | 8.2°C | 50 mm | 8 cm |
| May | 20°C | 7°C | 13.3°C | 67 mm | 1 cm |
| June | 26°C | 12°C | 18.7°C | 58 mm | 0 cm |
| July | 32°C | 15°C | 23.3°C | 29 mm | 0 cm |
| August | 31°C | 14°C | 22.4°C | 20 mm | 0 cm |
| September | 24°C | 9°C | 16.8°C | 42 mm | 0 cm |
| October | 16°C | 3°C | 9.6°C | 50 mm | 8 cm |
| November | 9°C | −2°C | 3.2°C | 20 mm | 15 cm |
| December | 4°C | −6°C | −0.9°C | 18 mm | 19 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00249240; 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 Yellowtail Dam?
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 USC00249240.
When is the last frost at Yellowtail Dam?
In Yellowtail Dam, the last spring frost (32°F) comes after May 7 in half of years and after May 24 in one year in ten; the first autumn frost comes before October 5 in half of years and before September 20 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 71 year in 10 after May 24; 9 in 10 after April 20
- First autumn frost, half of years before
- October 51 year in 10 before September 20; 9 in 10 before October 22
NOAA puts the median frost-free season at 151 days, and the season without a hard freeze (28°F) at 175 days.
A hard freeze (28°F) comes after April 24 in half of springs and before October 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Yellowtail Dam in zone 5a in ZIP code 59035, 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 5a: the coldest night of a typical year reaches −15°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 USC00249240; 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 Yellowtail Dam?
In a normal year in Yellowtail Dam, 45 days a year reach 90°F (6 of them 100°F or more), 126 nights fall to 32°F or colder and 66 days bring measurable precipitation.
- Days at 90°F or more
- 45a normal year
- Days at 100°F or more
- 6a normal year
- Nights at 32°F or colder
- 126a normal year
- Days that stay below freezing
- 29high of 32°F or less
- Days with 0.01 inch of precipitation
- 66a normal year
- Days with 1 inch of snow or more
- 9a normal year
The highest temperature in this station's record (since 1948) is 109°F, on July 14, 2005; the lowest is −32°F, on February 3, 1989.
The wettest calendar year on that record is 1964, with 26.54 in; the snowiest season is 1966–67, with 86.7 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00249240; records: ACIS (NOAA Regional Climate Centers), station USC00249240. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Yellowtail Dam?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds at Yellowtail Dam, 4.2 kWh per square metre a day. July is the sunniest month (89%) and April the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 75% | 1.8 |
| February | 77% | 2.8 |
| March | 73% | 3.9 |
| April | 70% | 4.9 |
| May | 72% | 5.9 |
| June | 80% | 6.9 |
| July | 89% | 7.3 |
| August | 86% | 6.1 |
| September | 81% | 4.6 |
| October | 73% | 2.9 |
| November | 73% | 1.9 |
| December | 70% | 1.4 |
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 Yellowtail Dam record?
A normal year at Yellowtail Dam brings 6,378 heating degree days, 19% more than the median U.S. place (5,373), and 734 cooling degree days, 19% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,762 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,115 | 0 |
| February | 966 | 0 |
| March | 803 | 0 |
| April | 550 | 2 |
| May | 299 | 18 |
| June | 78 | 95 |
| July | 9 | 288 |
| August | 22 | 250 |
| September | 151 | 71 |
| October | 497 | 9 |
| November | 815 | 0 |
| December | 1,074 | 0 |
| Year (annual) | 6,378 | 734 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00249240. 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 Yellowtail Dam been warmer than normal?
Over 37 complete years from 1949 to 2016, the station's annual mean temperature rose at a fitted 6.4°F per century (+0.35°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Yellowtail Dam's climate compare?
Yellowtail Dam is warmer than 141 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 49.4°F is warmer than 38%.
In the Köppen classification computed from these normals, Yellowtail Dam is Dfa: continental, no dry season, hot 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.
Which places near Yellowtail 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.
- Fort Smith, MT105 people · 0 mi NE
- St. Xavier, MT77 people · 14 mi NE
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 Yellowtail Dam's climate
What is the coldest month at Yellowtail Dam?
January, with a normal high of 39°F and a normal low of 20°F. The warmest is July (89°F by day, 59°F at night).
Does it snow at Yellowtail Dam?
Yes: 44 inches in a normal year, falling on 11 days with 0.1 inch or more, the most in January (8.8 inches).
What is the rainiest month at Yellowtail Dam?
May, with 2.62 in of precipitation in a normal year; the driest is January with 0.72 in.
What plant hardiness zone is Yellowtail Dam in?
The USDA's 2023 map puts Yellowtail Dam in zone 5a in ZIP code 59035, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −15°F (16 years, 1991-2020): zone 5a.
How late can frost come at Yellowtail Dam?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 24. Waiting until May 24 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Wyola, MT29 miles from this station, 46.0°F a year
- Hardin, MT33 miles from this station, 47.7°F a year
- Lovell, WY40 miles from this station, 44.9°F a year
- Burgess Junction, WY42 miles from this station, 34.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made