Chester, Montana climate: Normal weather by month, frost dates and records
Chester's normal year runs from 3°F January nights to 83°F July afternoons, with 12.3 inches of precipitation and 37 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.2°C, January lows of −16°C, July highs of 28°C, 312 mm of precipitation a year.
- NOAA stationChester
- Station IDUSC00241692
- Location48.51°N 110.97°W
- Elevation3,132 ft (955 m)
- Population835
On October 22, the normal high in Chester is 53°F and the normal low 24°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 Chester.
- Jan 29° 3°
- Feb 33° 6°
- Mar 44° 17°
- Apr 56° 28°
- May 66° 38°
- Jun 73° 46°
- Jul 83° 52°
- Aug 82° 50°
- Sep 71° 41°
- Oct 57° 27°
- Nov 41° 15°
- Dec 32° 6°
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 Chester each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 3°F. The most precipitation falls in June (2.76 in), the least in February (0.45 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 29°F | 3°F | 15.7°F | 0.54 | 8.3 | 5 | <1 | 31 | 8 h 40 min |
| February | 33°F | 6°F | 19.6°F | 0.45 | 5.7 | 5 | <1 | 28 | 10 h 10 min |
| March | 44°F | 17°F | 30.4°F | 0.59 | 5.1 | 6 | <1 | 30 | 11 h 50 min |
| April | 56°F | 28°F | 41.5°F | 1.10 | 3.7 | 7 | <1 | 22 | 13 h 40 min |
| May | 66°F | 38°F | 52.0°F | 1.68 | 0.4 | 10 | <1 | 7 | 15 h 10 min |
| June | 73°F | 46°F | 59.5°F | 2.76 | 0.1 | 12 | 1 | <1 | 16 h 10 min |
| July | 83°F | 52°F | 67.1°F | 1.19 | 0.0 | 6 | 7 | <1 | 15 h 50 min |
| August | 82°F | 50°F | 65.8°F | 1.09 | 0.0 | 6 | 7 | <1 | 14 h 20 min |
| September | 71°F | 41°F | 55.7°F | 1.00 | 0.6 | 6 | 1 | 4 | 12 h 40 min |
| October | 57°F | 27°F | 42.1°F | 0.74 | 0.7 | 6 | <1 | 20 | 11 h |
| November | 41°F | 15°F | 28.2°F | 0.58 | 5.6 | 5 | <1 | 28 | 9 h 20 min |
| December | 32°F | 6°F | 18.6°F | 0.56 | 6.3 | 5 | <1 | 31 | 8 h 20 min |
| Year (annual) | 55°F | 27°F | 41.3°F | 12.28 | 36.5 | 79 | 16 | 199 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −16°C | −9.1°C | 14 mm | 21 cm |
| February | 1°C | −14°C | −6.9°C | 11 mm | 14 cm |
| March | 7°C | −9°C | −0.9°C | 15 mm | 13 cm |
| April | 13°C | −2°C | 5.3°C | 28 mm | 9 cm |
| May | 19°C | 3°C | 11.1°C | 43 mm | 1 cm |
| June | 23°C | 8°C | 15.3°C | 70 mm | 0 cm |
| July | 28°C | 11°C | 19.5°C | 30 mm | 0 cm |
| August | 28°C | 10°C | 18.8°C | 28 mm | 0 cm |
| September | 22°C | 5°C | 13.2°C | 25 mm | 2 cm |
| October | 14°C | −3°C | 5.6°C | 19 mm | 2 cm |
| November | 5°C | −9°C | −2.1°C | 15 mm | 14 cm |
| December | 0°C | −15°C | −7.4°C | 14 mm | 16 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00241692; 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 Chester?
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 (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 USC00241692.
When is the last frost in Chester?
In Chester, the last spring frost (32°F) comes after May 24 in half of years and after June 9 in one year in ten; the first autumn frost comes before September 17 in half of years and before September 3 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 241 year in 10 after June 9; 9 in 10 after May 11
- First autumn frost, half of years before
- September 171 year in 10 before September 3; 9 in 10 before September 29
NOAA puts the median frost-free season at 115 days, and the season without a hard freeze (28°F) at 137 days.
A hard freeze (28°F) comes after May 11 in half of springs and before September 26 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Chester in zone 4a in ZIP code 59522, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Chester's NOAA station is in zone 3b: the coldest night of a typical year reaches −32°F (21 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 USC00241692; 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 Chester?
In a normal year in Chester, 16 days a year reach 90°F, 199 nights fall to 32°F or colder and 79 days bring measurable precipitation.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 199a normal year
- Days that stay below freezing
- 51high of 32°F or less
- Days with 0.01 inch of precipitation
- 79a normal year
- Days with 1 inch of snow or more
- 10a normal year
The highest temperature in this station's record (since 1900) is 105°F, on August 5, 1961; the lowest is −57°F, on January 25, 1950.
The wettest calendar year on that record is 2010, with 19.22 in; the snowiest season is 2017–18, with 105.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00241692; records: ACIS (NOAA Regional Climate Centers), station USC00241692. Records use complete months only; a month missing more than three days is left out.
How sunny is Chester?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Chester, 3.9 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 1.3 |
| February | 69% | 2.3 |
| March | 70% | 3.5 |
| April | 72% | 4.9 |
| May | 73% | 5.9 |
| June | 78% | 6.6 |
| July | 87% | 7.1 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 73% | 2.6 |
| November | 67% | 1.5 |
| December | 62% | 1.0 |
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 Chester need?
A normal year in Chester brings 8,848 heating degree days, 65% more than the median U.S. place (5,373), and 257 cooling degree days, 72% 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 1,719 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,530 | 0 |
| February | 1,271 | 0 |
| March | 1,074 | 0 |
| April | 705 | 0 |
| May | 408 | 5 |
| June | 189 | 22 |
| July | 53 | 118 |
| August | 73 | 99 |
| September | 290 | 12 |
| October | 712 | 0 |
| November | 1,106 | 0 |
| December | 1,438 | 0 |
| Year (annual) | 8,848 | 257 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00241692. 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 Chester been warmer than normal lately?
2025 averaged 43.3°F, 2.0°F above the 1991-2020 normal of 41.3°F. 3 of the 3 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 41.9°F | +0.6°F | 11.90 | 50.0 |
| 2024 | 44.8°F | +3.5°F | 14.73 | 42.4 |
| 2025 | 43.3°F | +2.0°F | 16.98 | 54.7 |
Over 51 complete years from 1901 to 2025, the station's annual mean temperature rose at a fitted 4.8°F per century (+0.26°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00241692; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Chester's climate compare?
Chester is warmer than 22 of the other 140 places with their own NOAA record in Montana, and wetter than 19. Across the 7,247 U.S. stations with normals, its annual mean of 41.3°F is warmer than 8%.
In the Köppen classification computed from these normals, Chester 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.
Questions about Chester's climate
What is the coldest month in Chester?
January, with a normal high of 29°F and a normal low of 3°F. The warmest is July (83°F by day, 52°F at night).
Does it snow in Chester?
Yes: 37 inches in a normal year, falling on 22 days with 0.1 inch or more, the most in January (8.3 inches).
What is the rainiest month in Chester?
June, with 2.76 in of precipitation in a normal year; the driest is February with 0.45 in.
What plant hardiness zone is Chester in?
The USDA's 2023 map puts Chester in zone 4a in ZIP code 59522, the nearest ZIP area. By the same method at Chester's NOAA station, the coldest night of a typical year reaches −32°F (21 years, 1991-2020): zone 3b.
How late can frost come in Chester?
In half of years the last 32°F night comes after May 24; in one year in ten it comes after June 9. Waiting until June 9 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Joplin, MT10 miles from this station, 42.3°F a year
- Tiber Dam, MT15 miles from this station, 44.6°F a year
- Rudyard (19 mi S), MT23 miles from this station, 40.6°F a year
- Dunkirk (19 mi NNE), MT27 miles from this station, 41.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made