Summit, South Dakota climate: Normal weather by month, frost dates and records
Summit's normal year runs from 2°F January nights to 82°F July afternoons, with 25.7 inches of precipitation and 59 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.9°C, January lows of −17°C, July highs of 28°C, 653 mm of precipitation a year.
- NOAA stationSummit (1 mi W)
- Station IDUSC00398116
- Location45.30°N 97.06°W
- Elevation1,955 ft (596 m)
- Population278
On October 23, the normal high in Summit is 53°F and the normal low 31°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Summit.
- Jan 21° 2°
- Feb 26° 6°
- Mar 39° 18°
- Apr 55° 30°
- May 68° 43°
- Jun 77° 54°
- Jul 82° 58°
- Aug 80° 56°
- Sep 73° 48°
- Oct 58° 34°
- Nov 40° 21°
- Dec 26° 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 Summit each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 2°F. The most precipitation falls in July (4.07 in), the least in January (0.65 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 21°F | 2°F | 11.4°F | 0.65 | 10.2 | 6 | <1 | 31 | 9 h 10 min |
| February | 26°F | 6°F | 15.9°F | 0.69 | 12.4 | 6 | <1 | 28 | 10 h 20 min |
| March | 39°F | 18°F | 28.5°F | 1.03 | 8.8 | 6 | <1 | 27 | 11 h 50 min |
| April | 55°F | 30°F | 42.5°F | 2.34 | 7.8 | 8 | <1 | 18 | 13 h 30 min |
| May | 68°F | 43°F | 55.5°F | 3.16 | 0.1 | 11 | <1 | 4 | 14 h 50 min |
| June | 77°F | 54°F | 65.3°F | 3.95 | 0.0 | 11 | 1 | <1 | 15 h 40 min |
| July | 82°F | 58°F | 70.0°F | 4.07 | 0.0 | 9 | 3 | <1 | 15 h 20 min |
| August | 80°F | 56°F | 68.3°F | 2.97 | 0.0 | 9 | 2 | <1 | 14 h 10 min |
| September | 73°F | 48°F | 60.5°F | 2.77 | 0.0 | 8 | 1 | 2 | 12 h 40 min |
| October | 58°F | 34°F | 45.9°F | 2.51 | 2.0 | 8 | <1 | 13 | 11 h |
| November | 40°F | 21°F | 30.3°F | 0.90 | 5.4 | 5 | <1 | 26 | 9 h 30 min |
| December | 26°F | 9°F | 17.2°F | 0.66 | 11.9 | 7 | <1 | 31 | 8 h 50 min |
| Year (annual) | 54°F | 32°F | 42.6°F | 25.70 | 58.6 | 93 | 7 | 180 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −6°C | −17°C | −11.4°C | 17 mm | 26 cm |
| February | −4°C | −14°C | −8.9°C | 18 mm | 31 cm |
| March | 4°C | −8°C | −1.9°C | 26 mm | 22 cm |
| April | 13°C | −1°C | 5.8°C | 59 mm | 20 cm |
| May | 20°C | 6°C | 13.1°C | 80 mm | 0 cm |
| June | 25°C | 12°C | 18.5°C | 100 mm | 0 cm |
| July | 28°C | 15°C | 21.1°C | 103 mm | 0 cm |
| August | 27°C | 13°C | 20.2°C | 75 mm | 0 cm |
| September | 23°C | 9°C | 15.8°C | 70 mm | 0 cm |
| October | 14°C | 1°C | 7.7°C | 64 mm | 5 cm |
| November | 4°C | −6°C | −0.9°C | 23 mm | 14 cm |
| December | −4°C | −13°C | −8.2°C | 17 mm | 30 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00398116; 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 Summit?
Normal highs sit between 65°F and 85°F in May, 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 USC00398116.
When is the last frost in Summit?
In Summit, the last spring frost (32°F) comes after May 14 in half of years and after May 28 in one year in ten; the first autumn frost comes before September 28 in half of years and before September 13 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 141 year in 10 after May 28; 9 in 10 after May 1
- First autumn frost, half of years before
- September 281 year in 10 before September 13; 9 in 10 before October 10
NOAA puts the median frost-free season at 136 days, and the season without a hard freeze (28°F) at 153 days.
A hard freeze (28°F) comes after May 4 in half of springs and before October 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Summit in zone 4a in ZIP code 57266, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Summit's NOAA station is in zone 4a: the coldest night of a typical year reaches −27°F (30 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 USC00398116; 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 Summit?
In a normal year in Summit, 7 days a year reach 90°F, 180 nights fall to 32°F or colder and 93 days bring measurable precipitation.
- Days at 90°F or more
- 7a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 180a normal year
- Days that stay below freezing
- 91high of 32°F or less
- Days with 0.01 inch of precipitation
- 93a normal year
- Days with 1 inch of snow or more
- 19a normal year
The highest temperature in this station's record (since 1956) is 103°F, on June 24, 1988; the lowest is −40°F, on February 9, 1994.
The wettest calendar year on that record is 2019, with 38.21 in; the snowiest season is 2010–11, with 103.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00398116; records: ACIS (NOAA Regional Climate Centers), station USC00398116. Records use complete months only; a month missing more than three days is left out.
How sunny is Summit?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Summit, 4.0 kWh per square metre a day. July is the sunniest month (83%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 78% | 1.9 |
| February | 82% | 3.0 |
| March | 73% | 3.9 |
| April | 72% | 4.9 |
| May | 71% | 5.6 |
| June | 76% | 6.3 |
| July | 83% | 6.6 |
| August | 81% | 5.5 |
| September | 78% | 4.2 |
| October | 70% | 2.7 |
| November | 70% | 1.8 |
| December | 65% | 1.3 |
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 Summit need?
A normal year in Summit brings 8,604 heating degree days, 60% more than the median U.S. place (5,373), and 482 cooling degree days, 47% 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 2,331 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,661 | 0 |
| February | 1,375 | 0 |
| March | 1,130 | 0 |
| April | 677 | 1 |
| May | 315 | 20 |
| June | 78 | 87 |
| July | 23 | 178 |
| August | 37 | 141 |
| September | 188 | 51 |
| October | 594 | 4 |
| November | 1,043 | 0 |
| December | 1,483 | 0 |
| Year (annual) | 8,604 | 482 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00398116. 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 Summit been warmer than normal lately?
2025 averaged 42.8°F, 0.2°F above the 1991-2020 normal of 42.6°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 45.6°F | +3.0°F | 29.06 | 33.4 |
| 2022 | 41.7°F | −0.9°F | 24.28 | 63.8 |
| 2023 | 44.2°F | +1.6°F | 25.34 | 73.6 |
| 2024 | 45.5°F | +2.9°F | 23.61 | 34.1 |
| 2025 | 42.8°F | +0.2°F | 29.54 | 39.1 |
Over 59 complete years from 1957 to 2025, the station's annual mean temperature rose at a fitted 4.1°F per century (+0.23°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00398116; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Summit's climate compare?
Summit is warmer than 5 of the other 99 places with their own NOAA record in South Dakota, and wetter than 72. Across the 7,247 U.S. stations with normals, its annual mean of 42.6°F is warmer than 11%.
In the Köppen classification computed from these normals, Summit 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 Summit share this climate record?
2 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.
- Ortley, SD50 people · 7 mi W
- Marvin, SD19 people · 8 mi SE
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 Summit's climate
What is the coldest month in Summit?
January, with a normal high of 21°F and a normal low of 2°F. The warmest is July (82°F by day, 58°F at night).
Does it snow in Summit?
Yes: 59 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in February (12.4 inches).
What is the rainiest month in Summit?
July, with 4.07 in of precipitation in a normal year; the driest is January with 0.65 in.
What plant hardiness zone is Summit in?
The USDA's 2023 map puts Summit in zone 4a in ZIP code 57266, the nearest ZIP area. By the same method at Summit's NOAA station, the coldest night of a typical year reaches −27°F (30 years, 1991-2020): zone 4a.
How late can frost come in Summit?
In half of years the last 32°F night comes after May 14; in one year in ten it comes after May 28. Waiting until May 28 leaves about a one-in-ten chance of a later frost.
Nearby and next
- South Dakota climateThe statewide normals and every place in the state
- Wilmot, SD12 miles from this station, 43.2°F a year
- Waubay, SD16 miles from this station, 44.1°F a year
- Milbank, SD22 miles from this station, 43.0°F a year
- Webster, SD22 miles from this station, 42.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made