Harlem, Montana climate: Normal weather by month, frost dates and records
Harlem's normal year runs from 5°F January nights to 85°F July afternoons, with 12.5 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.4°C, January lows of −15°C, July highs of 29°C, 318 mm of precipitation a year.
- NOAA stationHarlem
- Station IDUSC00243929
- Location48.54°N 108.80°W
- Elevation2,371 ft (723 m)
- Population757
On October 23, the normal high in Harlem is 56°F and the normal low 27°F, and the chance of measurable rain or snow is 16%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Harlem.
- Jan 28° 5°
- Feb 33° 9°
- Mar 45° 20°
- Apr 59° 30°
- May 69° 40°
- Jun 77° 49°
- Jul 85° 54°
- Aug 85° 52°
- Sep 74° 42°
- Oct 60° 30°
- Nov 43° 19°
- Dec 31° 9°
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 Harlem each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 5°F. The most precipitation falls in June (2.90 in), the least in February (0.36 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 28°F | 5°F | 16.6°F | 0.51 | 5 | <1 | 31 | 8 h 40 min |
| February | 33°F | 9°F | 20.8°F | 0.36 | 4 | <1 | 27 | 10 h 10 min |
| March | 45°F | 20°F | 32.5°F | 0.52 | 5 | <1 | 28 | 11 h 50 min |
| April | 59°F | 30°F | 44.4°F | 1.00 | 6 | <1 | 19 | 13 h 40 min |
| May | 69°F | 40°F | 54.3°F | 1.89 | 10 | 1 | 6 | 15 h 10 min |
| June | 77°F | 49°F | 62.6°F | 2.90 | 12 | 2 | <1 | 16 h 10 min |
| July | 85°F | 54°F | 69.3°F | 1.44 | 7 | 12 | <1 | 15 h 50 min |
| August | 85°F | 52°F | 68.2°F | 0.99 | 5 | 12 | <1 | 14 h 30 min |
| September | 74°F | 42°F | 57.9°F | 1.09 | 5 | 3 | 4 | 12 h 40 min |
| October | 60°F | 30°F | 45.1°F | 0.73 | 5 | <1 | 19 | 11 h |
| November | 43°F | 19°F | 31.1°F | 0.57 | 5 | <1 | 28 | 9 h 20 min |
| December | 31°F | 9°F | 19.8°F | 0.50 | 4 | <1 | 31 | 8 h 20 min |
| Year (annual) | 57°F | 30°F | 43.5°F | 12.50 | 72 | 30 | 192 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −15°C | −8.6°C | 13 mm |
| February | 0°C | −13°C | −6.2°C | 9 mm |
| March | 7°C | −7°C | 0.3°C | 13 mm |
| April | 15°C | −1°C | 6.9°C | 25 mm |
| May | 21°C | 4°C | 12.4°C | 48 mm |
| June | 25°C | 9°C | 17.0°C | 74 mm |
| July | 29°C | 12°C | 20.7°C | 37 mm |
| August | 29°C | 11°C | 20.1°C | 25 mm |
| September | 23°C | 5°C | 14.4°C | 28 mm |
| October | 15°C | −1°C | 7.3°C | 19 mm |
| November | 6°C | −7°C | −0.5°C | 14 mm |
| December | −1°C | −13°C | −6.8°C | 13 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 USC00243929; 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 Harlem?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August 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 USC00243929.
When is the last frost in Harlem?
In Harlem, the last spring frost (32°F) comes after May 16 in half of years and after May 31 in one year in ten; the first autumn frost comes before September 21 in half of years and before September 8 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 161 year in 10 after May 31; 9 in 10 after May 4
- First autumn frost, half of years before
- September 211 year in 10 before September 8; 9 in 10 before October 2
NOAA puts the median frost-free season at 125 days, and the season without a hard freeze (28°F) at 145 days.
A hard freeze (28°F) comes after May 6 in half of springs and before September 29 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Harlem in zone 4a in ZIP code 59526, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Harlem's NOAA station is in zone 3b: the coldest night of a typical year reaches −32°F (15 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00243929; 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 Harlem?
In a normal year in Harlem, 30 days a year reach 90°F (3 of them 100°F or more), 192 nights fall to 32°F or colder and 72 days bring measurable precipitation.
- Days at 90°F or more
- 30a normal year
- Days at 100°F or more
- 3a normal year
- Nights at 32°F or colder
- 192a normal year
- Days that stay below freezing
- 55high of 32°F or less
- Days with 0.01 inch of precipitation
- 72a normal year
The highest temperature in this station's record (since 1896) is 107°F, on June 4, 1988; the lowest is −50°F, on January 24, 1969.
The wettest calendar year on that record is 1938, with 20.50 in; the snowiest season is 1964–65, with 70.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00243929; records: ACIS (NOAA Regional Climate Centers), station USC00243929. Records use complete months only; a month missing more than three days is left out.
How sunny is Harlem?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Harlem, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (69%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 75% | 1.5 |
| February | 78% | 2.6 |
| March | 75% | 3.8 |
| April | 73% | 4.9 |
| May | 74% | 5.9 |
| June | 78% | 6.6 |
| July | 87% | 7.0 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 74% | 2.7 |
| November | 71% | 1.6 |
| December | 69% | 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 much heating and cooling does Harlem need?
A normal year in Harlem brings 8,168 heating degree days, 52% more than the median U.S. place (5,373), and 380 cooling degree days, 58% 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 2,071 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,500 | 0 |
| February | 1,238 | 0 |
| March | 1,009 | 0 |
| April | 620 | 0 |
| May | 339 | 8 |
| June | 117 | 46 |
| July | 29 | 161 |
| August | 45 | 142 |
| September | 235 | 22 |
| October | 619 | 0 |
| November | 1,017 | 0 |
| December | 1,401 | 0 |
| Year (annual) | 8,168 | 380 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00243929. 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.
How does Harlem's climate compare?
Harlem is warmer than 56 of the other 140 places with their own NOAA record in Montana, and wetter than 24. Across the 7,247 U.S. stations with normals, its annual mean of 43.5°F is warmer than 14%.
In the Köppen classification computed from these normals, Harlem 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 Harlem share this climate record?
North Harlem Colony 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.
- North Harlem Colony, MT47 people · 4 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.
What do Harlem's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Harlem. This page uses Harlem; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Harlem (20 mi S) USC00243934 | 21 mi S | 2,695 ft | 43.8°F | 8°F | 86°F | 14.3 | – | May 24 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Harlem's climate
What is the coldest month in Harlem?
January, with a normal high of 28°F and a normal low of 5°F. The warmest is July (85°F by day, 54°F at night).
What is the rainiest month in Harlem?
June, with 2.90 in of precipitation in a normal year; the driest is February with 0.36 in.
What plant hardiness zone is Harlem in?
The USDA's 2023 map puts Harlem in zone 4a in ZIP code 59526, the nearest ZIP area. By the same method at Harlem's NOAA station, the coldest night of a typical year reaches −32°F (15 years, 1991-2020): zone 3b.
How late can frost come in Harlem?
In half of years the last 32°F night comes after May 16; in one year in ten it comes after May 31. Waiting until May 31 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Fort Belknap (2 mi SW), MT5 miles from this station, 42.6°F a year
- Chinook, MT20 miles from this station, 42.4°F a year
- Chinook (35 mi SE), MT27 miles from this station, 43.2°F a year
- Turner (11 mi N), MT37 miles from this station, 42.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made