Hysham, Montana climate: Normal weather by month, frost dates and records
Hysham's normal year runs from 12°F January nights to 88°F July afternoons, with 14.9 inches of precipitation and 37 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.4°C, January lows of −11°C, July highs of 31°C, 379 mm of precipitation a year.
- NOAA stationHysham
- Station IDUSC00244358
- Location46.29°N 107.23°W
- Elevation2,669 ft (814 m)
- Population266
On October 23, the normal high in Hysham is 57°F and the normal low 31°F, and the chance of measurable rain or snow is 19%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Hysham.
- Jan 35° 12°
- Feb 39° 15°
- Mar 51° 24°
- Apr 61° 33°
- May 70° 43°
- Jun 79° 52°
- Jul 88° 58°
- Aug 86° 55°
- Sep 75° 46°
- Oct 60° 34°
- Nov 47° 23°
- Dec 36° 15°
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 Hysham each month?
July is the warmest month, with normal highs of 88°F; January the coldest, with normal lows of 12°F. The most precipitation falls in May (2.47 in), the least in December (0.48 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 35°F | 12°F | 23.6°F | 0.61 | 8.3 | 5 | <1 | 29 | 9 h |
| February | 39°F | 15°F | 27.0°F | 0.58 | 5.4 | 5 | <1 | 26 | 10 h 20 min |
| March | 51°F | 24°F | 37.1°F | 0.80 | 5.6 | 6 | <1 | 24 | 11 h 50 min |
| April | 61°F | 33°F | 46.8°F | 1.72 | 2.5 | 7 | <1 | 13 | 13 h 30 min |
| May | 70°F | 43°F | 56.1°F | 2.47 | 0.8 | 9 | <1 | 3 | 15 h |
| June | 79°F | 52°F | 65.2°F | 2.22 | 0.0 | 9 | 3 | <1 | 15 h 50 min |
| July | 88°F | 58°F | 72.5°F | 1.51 | 0.0 | 6 | 14 | <1 | 15 h 30 min |
| August | 86°F | 55°F | 70.6°F | 1.16 | 0.0 | 5 | 12 | <1 | 14 h 10 min |
| September | 75°F | 46°F | 60.4°F | 1.40 | 0.1 | 5 | 2 | 1 | 12 h 40 min |
| October | 60°F | 34°F | 47.3°F | 1.38 | 2.7 | 6 | <1 | 11 | 11 h |
| November | 47°F | 23°F | 34.9°F | 0.59 | 4.2 | 5 | <1 | 24 | 9 h 30 min |
| December | 36°F | 15°F | 25.4°F | 0.48 | 7.5 | 5 | <1 | 29 | 8 h 40 min |
| Year (annual) | 60°F | 34°F | 47.2°F | 14.92 | 37.1 | 72 | 31 | 161 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 2°C | −11°C | −4.7°C | 15 mm | 21 cm |
| February | 4°C | −9°C | −2.8°C | 15 mm | 14 cm |
| March | 10°C | −5°C | 2.8°C | 20 mm | 14 cm |
| April | 16°C | 1°C | 8.2°C | 44 mm | 6 cm |
| May | 21°C | 6°C | 13.4°C | 63 mm | 2 cm |
| June | 26°C | 11°C | 18.4°C | 56 mm | 0 cm |
| July | 31°C | 14°C | 22.5°C | 38 mm | 0 cm |
| August | 30°C | 13°C | 21.4°C | 29 mm | 0 cm |
| September | 24°C | 8°C | 15.8°C | 36 mm | 0 cm |
| October | 16°C | 1°C | 8.5°C | 35 mm | 7 cm |
| November | 8°C | −5°C | 1.6°C | 15 mm | 11 cm |
| December | 2°C | −10°C | −3.7°C | 12 mm | 19 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244358; 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 Hysham?
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 USC00244358.
When is the last frost in Hysham?
In Hysham, the last spring frost (32°F) comes after May 10 in half of years and after May 22 in one year in ten; the first autumn frost comes before September 29 in half of years and before September 15 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 101 year in 10 after May 22; 9 in 10 after April 28
- First autumn frost, half of years before
- September 291 year in 10 before September 15; 9 in 10 before October 11
NOAA puts the median frost-free season at 141 days, and the season without a hard freeze (28°F) at 161 days.
A hard freeze (28°F) comes after April 30 in half of springs and before October 7 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Hysham in zone 4b in ZIP code 59038, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Hysham's NOAA station is in zone 4b: the coldest night of a typical year reaches −24°F (29 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 USC00244358; 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 Hysham?
In a normal year in Hysham, 31 days a year reach 90°F (1 of them 100°F or more), 161 nights fall to 32°F or colder and 72 days bring measurable precipitation.
- Days at 90°F or more
- 31a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 161a normal year
- Days that stay below freezing
- 39high of 32°F or less
- Days with 0.01 inch of precipitation
- 72a normal year
- Days with 1 inch of snow or more
- 16a normal year
The highest temperature in this station's record (since 1945) is 111°F, on July 28, 1947; the lowest is −48°F, on January 20, 1954.
The wettest calendar year on that record is 1993, with 22.46 in; the snowiest season is 1995–96, with 77.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00244358; records: ACIS (NOAA Regional Climate Centers), station USC00244358. Records use complete months only; a month missing more than three days is left out.
How sunny is Hysham?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Hysham, 4.1 kWh per square metre a day. July is the sunniest month (89%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 71% | 1.6 |
| February | 73% | 2.6 |
| March | 70% | 3.6 |
| April | 71% | 4.9 |
| May | 74% | 6.0 |
| June | 80% | 6.8 |
| July | 89% | 7.2 |
| August | 87% | 6.0 |
| September | 81% | 4.4 |
| October | 74% | 2.9 |
| November | 73% | 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 much heating and cooling does Hysham need?
A normal year in Hysham brings 7,011 heating degree days, 30% more than the median U.S. place (5,373), and 573 cooling degree days, 37% 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 2,490 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,285 | 0 |
| February | 1,064 | 0 |
| March | 863 | 0 |
| April | 548 | 1 |
| May | 288 | 14 |
| June | 74 | 80 |
| July | 11 | 245 |
| August | 24 | 196 |
| September | 175 | 37 |
| October | 550 | 2 |
| November | 903 | 0 |
| December | 1,226 | 0 |
| Year (annual) | 7,011 | 573 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244358. 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 Hysham been warmer than normal lately?
2025 averaged 49.0°F, 1.8°F above the 1991-2020 normal of 47.2°F. 3 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 47.9°F | +0.7°F | 11.63 | 28.7 |
| 2023 | 49.6°F | +2.4°F | 17.49 | 23.3 |
| 2025 | 49.0°F | +1.8°F | 18.25 | 44.6 |
Over 59 complete years from 1946 to 2025, the station's annual mean temperature rose at a fitted 2.8°F per century (+0.15°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00244358; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Hysham's climate compare?
Hysham is warmer than 131 of the other 140 places with their own NOAA record in Montana, and wetter than 69. Across the 7,247 U.S. stations with normals, its annual mean of 47.2°F is warmer than 29%.
In the Köppen classification computed from these normals, Hysham 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 Hysham share this climate record?
Custer 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.
- Custer, MT155 people · 19 mi SW
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 Hysham's climate
What is the coldest month in Hysham?
January, with a normal high of 35°F and a normal low of 12°F. The warmest is July (88°F by day, 58°F at night).
Does it snow in Hysham?
Yes: 37 inches in a normal year, falling on 19 days with 0.1 inch or more, the most in January (8.3 inches).
What is the rainiest month in Hysham?
May, with 2.47 in of precipitation in a normal year; the driest is December with 0.48 in.
What plant hardiness zone is Hysham in?
The USDA's 2023 map puts Hysham in zone 4b in ZIP code 59038, the nearest ZIP area. By the same method at Hysham's NOAA station, the coldest night of a typical year reaches −24°F (29 years, 1991-2020): zone 4b.
How late can frost come in Hysham?
In half of years the last 32°F night comes after May 10; in one year in ten it comes after May 22. Waiting until May 22 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Ingomar (9 mi E), MT19 miles from this station, 44.2°F a year
- Hysham (25 mi SSE), MT25 miles from this station, 44.6°F a year
- Forsyth, MT27 miles from this station, 46.7°F a year
- Melstone, MT37 miles from this station, 47.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made