Custer, South Dakota climate: Normal weather by month, frost dates and records
Custer's normal year runs from 15°F January nights to 79°F July afternoons, with 19.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.2°C, January lows of −9°C, July highs of 26°C, 502 mm of precipitation a year.
- NOAA stationCuster County Airport
- Station IDUSW00094032
- Location43.73°N 103.61°W
- Elevation5,545 ft (1,690 m)
- Population1,829
On October 22, the normal high in Custer is 52°F and the normal low 30°F, and the chance of measurable rain or snow is 25%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Custer.
- Jan 35° 15°
- Feb 35° 15°
- Mar 44° 22°
- Apr 50° 29°
- May 60° 38°
- Jun 71° 47°
- Jul 79° 54°
- Aug 78° 52°
- Sep 69° 43°
- Oct 54° 32°
- Nov 43° 22°
- 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 Custer each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 15°F. The most precipitation falls in July (3.29 in), the least in January (0.41 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 35°F | 15°F | 25.1°F | 0.41 | 5 | <1 | 30 | 9 h 20 min |
| February | 35°F | 15°F | 25.1°F | 0.59 | 7 | <1 | 27 | 10 h 30 min |
| March | 44°F | 22°F | 32.9°F | 0.91 | 8 | <1 | 28 | 11 h 50 min |
| April | 50°F | 29°F | 39.3°F | 2.42 | 12 | <1 | 22 | 13 h 20 min |
| May | 60°F | 38°F | 48.6°F | 2.97 | 14 | <1 | 10 | 14 h 40 min |
| June | 71°F | 47°F | 58.9°F | 3.16 | 13 | 1 | 1 | 15 h 30 min |
| July | 79°F | 54°F | 66.5°F | 3.29 | 12 | 3 | <1 | 15 h 10 min |
| August | 78°F | 52°F | 64.7°F | 2.12 | 10 | 2 | <1 | 14 h |
| September | 69°F | 43°F | 55.9°F | 1.59 | 8 | <1 | 3 | 12 h 30 min |
| October | 54°F | 32°F | 43.0°F | 1.29 | 9 | <1 | 18 | 11 h 10 min |
| November | 43°F | 22°F | 32.6°F | 0.52 | 6 | <1 | 26 | 9 h 40 min |
| December | 35°F | 16°F | 25.2°F | 0.48 | 6 | <1 | 30 | 9 h |
| Year (annual) | 54°F | 32°F | 43.1°F | 19.75 | 109 | 6 | 195 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 2°C | −9°C | −3.8°C | 10 mm |
| February | 2°C | −9°C | −3.8°C | 15 mm |
| March | 6°C | −5°C | 0.5°C | 23 mm |
| April | 10°C | −2°C | 4.1°C | 61 mm |
| May | 15°C | 3°C | 9.2°C | 75 mm |
| June | 22°C | 8°C | 14.9°C | 80 mm |
| July | 26°C | 12°C | 19.2°C | 84 mm |
| August | 25°C | 11°C | 18.2°C | 54 mm |
| September | 21°C | 6°C | 13.3°C | 40 mm |
| October | 12°C | 0°C | 6.1°C | 33 mm |
| November | 6°C | −5°C | 0.3°C | 13 mm |
| December | 2°C | −9°C | −3.8°C | 12 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Custer's own co-op station Custer station does: 58 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094032; 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 Custer?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, September has the fewest days with rain (8).
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 USW00094032.
When is the last frost in Custer?
In Custer, the last spring frost (32°F) comes after May 23 in half of years and after June 6 in one year in ten; the first autumn frost comes before September 24 in half of years and before September 9 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 231 year in 10 after June 6; 9 in 10 after May 10
- First autumn frost, half of years before
- September 241 year in 10 before September 9; 9 in 10 before October 9
NOAA puts the median frost-free season at 122 days, and the season without a hard freeze (28°F) at 147 days.
A hard freeze (28°F) comes after May 10 in half of springs and before October 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Custer in zone 5a in ZIP code 57730, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Custer's NOAA station is in zone 5a: the coldest night of a typical year reaches −18°F (20 complete years).
Frost dates for every NOAA station in South Dakota · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00094032; 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 Custer?
In a normal year in Custer, 6 days a year reach 90°F, 195 nights fall to 32°F or colder and 109 days bring measurable precipitation.
- Days at 90°F or more
- 6a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 195a normal year
- Days that stay below freezing
- 50high of 32°F or less
- Days with 0.01 inch of precipitation
- 109a normal year
The highest temperature in this station's record (since 1999) is 99°F, on July 30, 2006; the lowest is −33°F, on December 22, 2022.
The wettest calendar year on that record is 2019, with 27.21 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00094032; records: ACIS (NOAA Regional Climate Centers), station USW00094032. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Custer, and how clear are its skies?
The summer (June-August) dew point averages 46°F. The muggiest month is July, with an average dew point of 49°F; the driest air comes in December (11°F). January is the windiest month (7.1 mph on average).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 12°F | 56% | 44% | 7.1 mph | – | – |
| February | 13°F | 56% | 41% | 6.8 mph | – | – |
| March | 21°F | 56% | 40% | 6.8 mph | – | – |
| April | 28°F | 58% | 43% | 7.1 mph | – | – |
| May | 40°F | 62% | 46% | 6.9 mph | – | – |
| June | 47°F | 56% | 41% | 6.2 mph | – | – |
| July | 49°F | 56% | 39% | 5.8 mph | – | – |
| August | 42°F | 49% | 32% | 5.9 mph | – | – |
| September | 32°F | 52% | 36% | 6.2 mph | – | – |
| October | 20°F | 52% | 38% | 6.5 mph | – | – |
| November | 13°F | 55% | 44% | 6.9 mph | – | – |
| December | 11°F | 56% | 44% | 6.9 mph | – | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094032. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Custer?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Custer, 4.4 kWh per square metre a day. July is the sunniest month (86%) and April the cloudiest (72%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 78% | 2.1 |
| February | 75% | 3.0 |
| March | 74% | 4.1 |
| April | 72% | 5.1 |
| May | 73% | 6.0 |
| June | 82% | 7.0 |
| July | 86% | 7.1 |
| August | 86% | 6.1 |
| September | 83% | 4.8 |
| October | 77% | 3.3 |
| November | 77% | 2.3 |
| December | 75% | 1.8 |
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 Custer need?
A normal year in Custer brings 8,152 heating degree days, 52% more than the median U.S. place (5,373), and 210 cooling degree days, 77% 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 1,624 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,237 | 0 |
| February | 1,117 | 0 |
| March | 997 | 0 |
| April | 771 | 0 |
| May | 511 | 1 |
| June | 209 | 26 |
| July | 50 | 95 |
| August | 81 | 71 |
| September | 288 | 16 |
| October | 684 | 0 |
| November | 974 | 0 |
| December | 1,234 | 0 |
| Year (annual) | 8,152 | 210 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094032. 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 Custer been warmer than normal lately?
2025 averaged 44.3°F, 1.2°F above the 1991-2020 normal of 43.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 44.2°F | +1.1°F | 18.73 |
| 2022 | 42.9°F | −0.3°F | 15.84 |
| 2023 | 43.8°F | +0.7°F | 23.93 |
| 2024 | 46.0°F | +2.9°F | 14.42 |
| 2025 | 44.3°F | +1.2°F | 17.35 |
Source: observed years: ACIS, station USW00094032. A year counts only with all twelve months complete.
How does Custer's climate compare?
Custer is warmer than 14 of the other 99 places with their own NOAA record in South Dakota, and wetter than 24. Across the 7,247 U.S. stations with normals, its annual mean of 43.1°F is warmer than 12%.
In the Köppen classification computed from these normals, Custer 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.
What do Custer's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Custer. This page uses Custer County Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Custer station USC00392087 | 3 mi N | 5,480 ft | 44.9°F | 16°F | 80°F | 20.7 | 58 | May 18 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Custer's climate
What is the coldest month in Custer?
January, with a normal high of 35°F and a normal low of 15°F. The warmest is July (79°F by day, 54°F at night).
Does it snow in Custer?
Yes. NOAA publishes no 1991-2020 snowfall normal for Custer's NOAA station; Custer's own co-op station Custer station records 58 inches of snow in a normal year.
What is the rainiest month in Custer?
July, with 3.29 in of precipitation in a normal year; the driest is January with 0.41 in.
What plant hardiness zone is Custer in?
The USDA's 2023 map puts Custer in zone 5a in ZIP code 57730, the nearest ZIP area. By the same method at Custer's NOAA station, the coldest night of a typical year reaches −18°F (20 years, 1991-2020): zone 5a.
How late can frost come in Custer?
In half of years the last 32°F night comes after May 23; in one year in ten it comes after June 6. Waiting until June 6 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Custer in OctoberThis month day by day, its records and recent years
- South Dakota climateThe statewide normals and every place in the state
- Mount Rushmore National Memorial, SD12 miles from this station, 45.7°F a year
- Wind Cave, SD14 miles from this station, 47.2°F a year
- Hill City, SD14 miles from this station, 43.9°F a year
- Hot Springs, SD22 miles from this station, 48.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made