Zortman, Montana climate: Normal weather by month, frost dates and records
Zortman's normal year runs from 14°F January nights to 79°F July afternoons, with 19.5 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.2°C, January lows of −10°C, July highs of 26°C, 494 mm of precipitation a year.
- NOAA stationZortman
- Station IDUSC00249900
- Location47.92°N 108.52°W
- Elevation4,035 ft (1,230 m)
- From the centerunder 1 mile
- Population (census place)63
On October 22, the normal high in Zortman is 51°F and the normal low 31°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Zortman.
- Jan 34° 14°
- Feb 34° 15°
- Mar 43° 22°
- Apr 51° 30°
- May 61° 39°
- Jun 69° 47°
- Jul 79° 54°
- Aug 79° 52°
- Sep 68° 43°
- Oct 54° 33°
- Nov 42° 24°
- Dec 35° 16°
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 Zortman each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 14°F. The most precipitation falls in June (4.00 in), the least in February (0.63 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 34°F | 14°F | 23.9°F | 0.92 | – | <1 | 28 | 8 h 50 min |
| February | 34°F | 15°F | 24.4°F | 0.63 | – | <1 | 27 | 10 h 10 min |
| March | 43°F | 22°F | 32.2°F | 0.83 | – | <1 | 27 | 11 h 50 min |
| April | 51°F | 30°F | 40.6°F | 1.77 | – | <1 | 21 | 13 h 40 min |
| May | 61°F | 39°F | 50.0°F | 3.18 | – | <1 | 8 | 15 h 10 min |
| June | 69°F | 47°F | 58.4°F | 4.00 | – | <1 | 1 | 16 h |
| July | 79°F | 54°F | 66.3°F | 2.32 | – | 4 | <1 | 15 h 40 min |
| August | 79°F | 52°F | 65.7°F | 1.45 | – | 4 | <1 | 14 h 20 min |
| September | 68°F | 43°F | 55.6°F | 1.37 | – | 1 | 4 | 12 h 40 min |
| October | 54°F | 33°F | 43.1°F | 1.29 | – | <1 | 17 | 11 h |
| November | 42°F | 24°F | 33.2°F | 0.99 | – | <1 | 24 | 9 h 20 min |
| December | 35°F | 16°F | 25.4°F | 0.71 | – | <1 | 28 | 8 h 30 min |
| Year (annual) | 54°F | 33°F | 43.2°F | 19.46 | – | 9 | 186 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 1°C | −10°C | −4.5°C | 23 mm |
| February | 1°C | −10°C | −4.2°C | 16 mm |
| March | 6°C | −6°C | 0.1°C | 21 mm |
| April | 11°C | −1°C | 4.8°C | 45 mm |
| May | 16°C | 4°C | 10.0°C | 81 mm |
| June | 21°C | 9°C | 14.7°C | 102 mm |
| July | 26°C | 12°C | 19.1°C | 59 mm |
| August | 26°C | 11°C | 18.7°C | 37 mm |
| September | 20°C | 6°C | 13.1°C | 35 mm |
| October | 12°C | 0°C | 6.2°C | 33 mm |
| November | 6°C | −5°C | 0.7°C | 25 mm |
| December | 1°C | −9°C | −3.7°C | 18 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 USC00249900; 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 Zortman?
Normal highs sit between 65°F and 85°F in June, July, August and September.
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 USC00249900.
When is the last frost in Zortman?
In Zortman, the last spring frost (32°F) comes after May 18 in half of years and after June 1 in one year in ten; the first autumn frost comes before September 23 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 181 year in 10 after June 1; 9 in 10 after May 4
- First autumn frost, half of years before
- September 231 year in 10 before September 7; 9 in 10 before October 5
NOAA puts the median frost-free season at 126 days, and the season without a hard freeze (28°F) at 149 days.
A hard freeze (28°F) comes after May 5 in half of springs and before October 2 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Zortman in zone 4b in ZIP code 59546, the nearest ZIP area.
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00249900; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Zortman?
In a normal year in Zortman, 9 days a year reach 90°F and 186 nights fall to 32°F or colder.
- Days at 90°F or more
- 9a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 186a normal year
- Days that stay below freezing
- 49high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00249900.
How sunny is Zortman?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Zortman, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 73% | 1.6 |
| February | 75% | 2.6 |
| March | 72% | 3.7 |
| April | 70% | 4.8 |
| May | 72% | 5.8 |
| June | 77% | 6.6 |
| July | 87% | 7.1 |
| August | 85% | 5.9 |
| September | 79% | 4.3 |
| October | 73% | 2.7 |
| November | 71% | 1.7 |
| December | 67% | 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 much heating and cooling does Zortman need?
A normal year in Zortman brings 8,163 heating degree days, 52% more than the median U.S. place (5,373), and 260 cooling degree days, 71% fewer than the median (908). Nine months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,675 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,274 | 0 |
| February | 1,135 | 0 |
| March | 1,017 | 0 |
| April | 732 | 0 |
| May | 468 | 3 |
| June | 217 | 18 |
| July | 68 | 110 |
| August | 84 | 106 |
| September | 306 | 23 |
| October | 678 | 1 |
| November | 956 | 0 |
| December | 1,227 | 0 |
| Year (annual) | 8,163 | 260 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00249900. 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 Zortman been warmer than normal lately?
2023 averaged 44.4°F, 1.2°F above the 1991-2020 normal of 43.2°F. 1 of the 2 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2022 | 42.4°F | −0.8°F | 21.05 |
| 2023 | 44.4°F | +1.2°F | 20.77 |
Source: observed years: ACIS, station USC00249900. A year counts only with all twelve months complete.
How does Zortman's climate compare?
Zortman is warmer than 52 of the other 140 places with their own NOAA record in Montana, and wetter than 114. Across the 7,247 U.S. stations with normals, its annual mean of 43.2°F is warmer than 13%.
In the Köppen classification computed from these normals, Zortman 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.
Which places near Zortman share this climate record?
3 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.
- Hays, MT967 people · 9 mi NW
- Lodge Pole, MT257 people · 8 mi N
- Landusky, MT29 people · 5 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 Zortman's climate
What is the coldest month in Zortman?
January, with a normal high of 34°F and a normal low of 14°F. The warmest is July (79°F by day, 54°F at night).
What is the rainiest month in Zortman?
June, with 4.00 in of precipitation in a normal year; the driest is February with 0.63 in.
What plant hardiness zone is Zortman in?
The USDA's 2023 map puts Zortman in zone 4b in ZIP code 59546, the nearest ZIP area.
How late can frost come in Zortman?
In half of years the last 32°F night comes after May 18; in one year in ten it comes after June 1. Waiting until June 1 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Sand Creek, MT25 miles from this station, 44.8°F a year
- Malta (35 mi S), MT27 miles from this station, 43.5°F a year
- Chinook (35 mi SE), MT29 miles from this station, 43.2°F a year
- Roy, MT33 miles from this station, 45.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made