Watertown, South Dakota climate: Normal weather by month, frost dates and records
Watertown's normal year runs from 3°F January nights to 82°F July afternoons, with 22.7 inches of precipitation and 41 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.1°C, January lows of −16°C, July highs of 28°C, 577 mm of precipitation a year.
- NOAA stationWatertown Regional Airport
- Station IDUSW00014946
- Location44.90°N 97.15°W
- Elevation1,748 ft (533 m)
- Population23,492
On October 23, the normal high in Watertown is 52°F and the normal low 32°F, and the chance of measurable rain or snow is 22%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Watertown.
- Jan 21° 3°
- Feb 26° 7°
- Mar 39° 20°
- Apr 54° 32°
- May 67° 45°
- Jun 77° 55°
- Jul 82° 60°
- Aug 80° 58°
- Sep 72° 49°
- Oct 56° 35°
- 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 Watertown each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 3°F. The most precipitation falls in June (3.85 in), the least in January (0.58 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. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 21°F | 3°F | 12.2°F | 0.58 | 6.7 | 6 | <1 | 31 | 9 h 10 min |
| February | 26°F | 7°F | 16.3°F | 0.65 | 8.9 | 6 | <1 | 28 | 10 h 20 min |
| March | 39°F | 20°F | 29.1°F | 1.00 | 5.4 | 7 | <1 | 27 | 11 h 50 min |
| April | 54°F | 32°F | 42.8°F | 2.06 | 5.2 | 9 | <1 | 16 | 13 h 30 min |
| May | 67°F | 45°F | 55.7°F | 2.87 | 0.1 | 11 | <1 | 2 | 14 h 50 min |
| June | 77°F | 55°F | 66.1°F | 3.85 | 0.0 | 11 | 2 | <1 | 15 h 30 min |
| July | 82°F | 60°F | 71.0°F | 3.05 | 0.0 | 10 | 4 | <1 | 15 h 20 min |
| August | 80°F | 58°F | 68.5°F | 2.89 | 0.0 | 9 | 3 | <1 | 14 h 10 min |
| September | 72°F | 49°F | 60.1°F | 2.45 | 0.0 | 9 | 1 | 1 | 12 h 40 min |
| October | 56°F | 35°F | 45.7°F | 1.95 | 1.4 | 8 | <1 | 12 | 11 h |
| November | 40°F | 21°F | 30.6°F | 0.68 | 4.5 | 5 | <1 | 26 | 9 h 40 min |
| December | 26°F | 9°F | 17.8°F | 0.68 | 8.9 | 6 | <1 | 31 | 8 h 50 min |
| Year (annual) | 53°F | 33°F | 43.0°F | 22.71 | 41.1 | 96 | 9 | 174 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −6°C | −16°C | −11.0°C | 15 mm | 17 cm |
| February | −3°C | −14°C | −8.7°C | 17 mm | 23 cm |
| March | 4°C | −7°C | −1.6°C | 25 mm | 14 cm |
| April | 12°C | 0°C | 6.0°C | 52 mm | 13 cm |
| May | 19°C | 7°C | 13.2°C | 73 mm | 0 cm |
| June | 25°C | 13°C | 18.9°C | 98 mm | 0 cm |
| July | 28°C | 16°C | 21.7°C | 77 mm | 0 cm |
| August | 26°C | 14°C | 20.3°C | 73 mm | 0 cm |
| September | 22°C | 9°C | 15.6°C | 62 mm | 0 cm |
| October | 13°C | 2°C | 7.6°C | 50 mm | 4 cm |
| November | 4°C | −6°C | −0.8°C | 17 mm | 11 cm |
| December | −3°C | −13°C | −7.9°C | 17 mm | 23 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014946; 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 Watertown?
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 (9).
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 USW00014946.
When is the last frost in Watertown?
In Watertown, the last spring frost (32°F) comes after May 7 in half of years and after May 20 in one year in ten; the first autumn frost comes before September 30 in half of years and before September 19 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 71 year in 10 after May 20; 9 in 10 after April 26
- First autumn frost, half of years before
- September 301 year in 10 before September 19; 9 in 10 before October 13
NOAA puts the median frost-free season at 145 days, and the season without a hard freeze (28°F) at 164 days.
A hard freeze (28°F) comes after April 29 in half of springs and before October 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Watertown in zone 4b in ZIP code 57201, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Watertown's NOAA station is in zone 4b: the coldest night of a typical year reaches −24°F (29 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 USW00014946; 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 Watertown?
In a normal year in Watertown, 9 days a year reach 90°F, 174 nights fall to 32°F or colder and 96 days bring measurable precipitation.
- Days at 90°F or more
- 9a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 174a normal year
- Days that stay below freezing
- 84high of 32°F or less
- Days with 0.01 inch of precipitation
- 96a normal year
- Days with 1 inch of snow or more
- 13a normal year
The highest temperature in this station's record (since 1893) is 110°F, on July 21, 1934; the lowest is −40°F, on January 13, 1916.
The wettest calendar year on that record is 1977, with 40.04 in; the snowiest season is 2018–19, with 81.7 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014946; records: ACIS (NOAA Regional Climate Centers), station USW00014946. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Watertown, and how clear are its skies?
The summer (June-August) dew point averages 59°F. The muggiest month is July, with an average dew point of 60°F; the driest air comes in December (10°F). March is the windiest month (12.3 mph on average), and August has the most clear or nearly clear hours (77%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 10°F | 81% | 74% | 10.6 mph | 58% | 33% |
| February | 14°F | 79% | 69% | 11.1 mph | 57% | 34% |
| March | 27°F | 69% | 51% | 12.3 mph | 58% | 30% |
| April | 36°F | 60% | 42% | 11.7 mph | 60% | 28% |
| May | 50°F | 66% | 50% | 10.0 mph | 59% | 25% |
| June | 59°F | 69% | 52% | 9.8 mph | 74% | 12% |
| July | 60°F | 71% | 52% | 8.4 mph | 76% | 11% |
| August | 57°F | 72% | 51% | 9.5 mph | 77% | 13% |
| September | 42°F | 67% | 47% | 10.5 mph | 70% | 21% |
| October | 30°F | 72% | 54% | 11.3 mph | 62% | 31% |
| November | 18°F | 79% | 67% | 10.9 mph | 60% | 32% |
| December | 10°F | 82% | 76% | 10.8 mph | 55% | 37% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014946. 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 Watertown?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Watertown, 4.1 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 77% | 2.0 |
| February | 79% | 3.0 |
| March | 71% | 3.8 |
| April | 71% | 4.9 |
| May | 72% | 5.7 |
| June | 77% | 6.4 |
| July | 85% | 6.7 |
| August | 82% | 5.6 |
| September | 79% | 4.4 |
| October | 73% | 2.9 |
| November | 73% | 2.0 |
| December | 67% | 1.4 |
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 Watertown need?
A normal year in Watertown brings 8,501 heating degree days, 58% more than the median U.S. place (5,373), and 518 cooling degree days, 43% 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 2,370 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,635 | 0 |
| February | 1,363 | 0 |
| March | 1,113 | 0 |
| April | 668 | 1 |
| May | 310 | 22 |
| June | 69 | 102 |
| July | 16 | 202 |
| August | 35 | 144 |
| September | 193 | 46 |
| October | 601 | 3 |
| November | 1,034 | 0 |
| December | 1,463 | 0 |
| Year (annual) | 8,501 | 518 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014946. 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 Watertown been warmer than normal lately?
2025 averaged 44.9°F, 1.9°F above the 1991-2020 normal of 43.0°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 45.8°F | +2.8°F | 26.79 | 30.7 |
| 2022 | 42.4°F | −0.6°F | 20.92 | 31.8 |
| 2023 | 45.0°F | +2.0°F | 19.44 | 35.3 |
| 2024 | 46.4°F | +3.4°F | 24.97 | 25.0 |
| 2025 | 44.9°F | +1.9°F | 28.94 | 37.4 |
Over 112 complete years from 1898 to 2025, the station's annual mean temperature rose at a fitted 3.0°F per century (+0.16°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00014946; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Watertown's climate compare?
Watertown is warmer than 11 of the other 99 places with their own NOAA record in South Dakota, and wetter than 50. Across the 7,247 U.S. stations with normals, its annual mean of 43.0°F is warmer than 12%.
In the Köppen classification computed from these normals, Watertown 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 Watertown 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.
- Kranzburg, SD166 people · 12 mi E
- Hazel, SD98 people · 15 mi SW
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 Watertown's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Watertown. This page uses Watertown Regional Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Watertown (2 mi S) USC00398931 | 3 mi SE | 1,772 ft | 43.7°F | 4°F | 82°F | 24.6 | – | May 3 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Watertown's climate
What is the coldest month in Watertown?
January, with a normal high of 21°F and a normal low of 3°F. The warmest is July (82°F by day, 60°F at night).
Does it snow in Watertown?
Yes: 41 inches in a normal year, falling on 27 days with 0.1 inch or more, the most in February (8.9 inches).
What is the rainiest month in Watertown?
June, with 3.85 in of precipitation in a normal year; the driest is January with 0.58 in.
What plant hardiness zone is Watertown in?
The USDA's 2023 map puts Watertown in zone 4b in ZIP code 57201, the nearest ZIP area. By the same method at Watertown's NOAA station, the coldest night of a typical year reaches −24°F (29 years, 1991-2020): zone 4b.
How late can frost come in Watertown?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 20. Waiting until May 20 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Watertown in OctoberThis month day by day, its records and recent years
- South Dakota climateThe statewide normals and every place in the state
- Rauville (2 mi W), SD5 miles from this station, 42.7°F a year
- Castlewood, SD14 miles from this station, 42.7°F a year
- Clear Lake, SD25 miles from this station, 42.4°F a year
- Summit, SD28 miles from this station, 42.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made