Custer County, SD Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Custer County's primary NOAA station, CUSTER CO AP.
The climate verdict for Custer County
Dryness leads the climate profile for Custer County, South Dakota, with 19.8 inches of precipitation a year. NOAA records an annual average of 43°F. At 40/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 6% of scores.
- 43°F
- average temperature, NOAA 1991-2020 normal
- 40/100
- comfort score, above 6% of station-mapped location scores
- 19.8"
- annual precipitation
- 124 days
- frost-free days per growing season
Custer County: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00094032 · Custer County, SD 43°F mean · 19.8" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 43°F
- RANK-COOL #823
- PHOTO-FINISH ≈ Saint Anthony
- PRCP-DRY 19.8"
- SWING-MID 41°F
- COMF-LOW 40/100
- LOAD-HEAT 8,152 HDD
- STN-1 USW00094032
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Saint Anthony, ID (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every SD station list.
- Custer County (this station) 43°F
- Hot Old Town, ME 43°F
- Near Saint Anthony, ID 43°F
- Near Rawlins, WY 43°F
- Near Lewistown, MT 43°F
Climate Living Index · Custer County
Custer County: 28/100 · grade F
Custer County publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals · NOAA hourly normals); 1 missing weight rescale to 100.
PlainClimate-derived for Custer County, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Summer moisture balance | 46.0°F mean dew point | 72/100 · B |
| Precipitation balance | 19.8 in · 15.3 from 35 in | 46/100 · D |
| Normal heat + freeze calendar | 199 calendar days | 14/100 · F |
| Annual temperature balance | 43.1°F · 24.4° from 67.5°F | 13/100 · F |
| Frost-free season | 124 days/year | 9/100 · F |
Custer County · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Custer County is a continental Köppen climate: Dfb
Coldest-month mean 25.1°F and warmest-month mean 66.5°F place this station in continental, no dry season, warm summer climates (Dfb). Class Dfb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, warm summer.
- Köppen code
- Dfb
- Group
- Continental
- Warmest month
- 66.5°F
- Coldest month
- 25.1°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Custer County sits across the climate record
Three NOAA fields for Custer County's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 88%
- Among 6,861 stations, Custer County sits in the cooler third of annual means.
- Annual precipitation
- Drier than 73%
- Custer County's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 42nd percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Custer County compares across U.S. station-mapped locations
Custer County's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
40 6th percentile score exceeds 6% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 35°F (2°C) | 15°F (-9°C) | 25°F (-4°C) | 0.4" | 30.4 | 0.0 |
| February | 35°F (2°C) | 15°F (-9°C) | 25°F (-4°C) | 0.6" | 27.0 | 0.0 |
| March | 44°F (6°C) | 22°F (-5°C) | 33°F (0°C) | 0.9" | 27.9 | 0.0 |
| April | 50°F (10°C) | 29°F (-2°C) | 39°F (4°C) | 2.4" | 21.7 | 0.0 |
| May | 60°F (15°C) | 38°F (3°C) | 49°F (9°C) | 3.0" | 10.4 | 0.0 |
| June | 71°F (22°C) | 47°F (8°C) | 59°F (15°C) | 3.2" | 0.6 | 0.8 |
| July | 79°F (26°C) | 54°F (12°C) | 67°F (19°C) | 3.3" | 0.0 | 3.0 |
| August | 78°F (25°C) | 52°F (11°C) | 65°F (18°C) | 2.1" | 0.1 | 1.8 |
| September | 69°F (21°C) | 43°F (6°C) | 56°F (13°C) | 1.6" | 3.0 | 0.1 |
| October | 54°F (12°C) | 32°F (0°C) | 43°F (6°C) | 1.3" | 18.2 | 0.0 |
| November | 43°F (6°C) | 22°F (-5°C) | 33°F (0°C) | 0.5" | 25.5 | 0.0 |
| December | 35°F (2°C) | 16°F (-9°C) | 25°F (-4°C) | 0.5" | 30.0 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 80°F around July 18, short of 90°F on every date, while 199 dates carry a normal low at or below freezing, the coldest 14°F near February 4.
The freezing stretch
The normal low stays at or below 32°F into April 30, then returns to freezing around October 15, covering 199 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is May 22, when 47% of years recorded at least a hundredth of an inch. The driest is January 6 at 17%. Summed across the calendar, that is about 109 wet dates a year.
The widest day
August 30 carries the biggest normal gap between afternoon and dawn, 28°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Custer County.
Where Custer County Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 199 nights a year, placing this among the most frost-prone tenth of ranked stations.
Custer County earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall
5.4 days with precipitation
7.2 days with precipitation
8.0 days with precipitation
11.5 days with precipitation
14.3 days with precipitation
12.6 days with precipitation
12.0 days with precipitation
10.0 days with precipitation
8.1 days with precipitation
8.5 days with precipitation
5.6 days with precipitation
5.9 days with precipitation
Custer County runs a summer-peaked wet season
43% of Custer County's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is July at 3.3", on a 41.4°F seasonal spread. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: July, June, May, taking 48% of the annual total between them.
- Driest month: January at 0.4".
- Winter share: 7% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
Custer County is dry, and what does fall arrives gently
Only about 109 days a year record measurable precipitation here, 30% of the calendar, and they carry 19.8" between them. At roughly 0.18 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is May at about 14 wet days; the driest is January at about 5.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Frost Dates & Growing Season
First Fall Freeze
September 24
50% probability date
Last Spring Freeze
May 23
50% probability date
Growing Season
124 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
8,152
Higher = more heating needed
Cooling Degree Days
210
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Humidity & Wind
Monthly averages from hourly observations
| Month | Humidity | Wind (mph) | Clear Sky % | Overcast % |
|---|---|---|---|---|
| January | 56% | 7.1 | N/A | N/A |
| February | 56% | 6.8 | N/A | N/A |
| March | 56% | 6.8 | N/A | N/A |
| April | 58% | 7.1 | N/A | N/A |
| May | 62% | 6.9 | N/A | N/A |
| June | 56% | 6.2 | N/A | N/A |
| July | 56% | 5.8 | N/A | N/A |
| August | 49% | 5.9 | N/A | N/A |
| September | 52% | 6.2 | N/A | N/A |
| October | 52% | 6.5 | N/A | N/A |
| November | 55% | 6.9 | N/A | N/A |
| December | 56% | 6.9 | N/A | N/A |
Nationwide similar cities
Other rankable U.S. places outside SD closest to Custer County on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (43°F here).
- Almont, ND 43°F · 0.0°F off
- Bismarck, ND 43°F · 0.0°F off
- Grantsburg, WI 43°F · 0.0°F off
- Hoonah, AK 43°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (19.8" here), excluding temperature-peer places.
- Gilroy, CA 19.8" · 0.0" off
- Hugoton, KS 19.7" · 0.0" off
- Imperial, NE 19.8" · 0.0" off
- Del Rio, TX 19.8" · 0.0" off
Data-derived climate profile
How Custer County's climate pattern fits together
heating led · dry · mid swing
Custer County's energy balance leans toward cold weather: 8,152 annual heating degree days against 210 for cooling. Its 41.4°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 124 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
July and January mark the typical warm and cold ends of the calendar in Custer County's middle-range seasonal profile. The measured spread is 41.4°F. The annual average is 43°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Custer County's cold-season load does not imply a wet climate. Annual precipitation is 19.8 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
These labels group NOAA 1991-2020 normals from Custer County's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Custer County, not an official NOAA class or a year-ahead forecast.
Questions about Custer County's climate
How much rain does Custer County get? ▼
How cold does Custer County get in winter? ▼
How much energy does heating and cooling require in Custer County? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Custer County's primary station: CUSTER CO AP (USW00094032). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Custer County; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Custer County comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.