Watertown weather in September: Watertown, South Dakota: normal highs, lows, rain and records for September
Watertown in September has a normal high of 72°F and a normal low of 49°F, a daily mean of 60°F, falling from 77°F on the 1st to 65°F by the 30th. Measurable precipitation falls on 9 days in a normal September, 2.45 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 9°C, 62 mm of precipitation in September.
- NOAA stationWatertown Regional Airport
- Station IDUSW00014946
- Location44.90°N 97.15°W
- Elevation1,748 ft (533 m)
- Population23,492
- 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.
How warm is Watertown in September?
The normal high is 72°F and the normal low 49°F, for a daily mean of 60.1°F. September is 8.4°F cooler than August and 14.4°F warmer than October. September is the 4th warmest month of the year in Watertown and the 5th wettest. Across the month the normal high falls 12°F, from 77°F on September 1 to 65°F on September 30. From one year to the next September's mean temperature typically moves about 2.8°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 57°F and 63°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 28%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 77°F | 54°F | 28% | 15% |
| September 8 | 75°F | 52°F | 28% | 16% |
| September 15 | 72°F | 49°F | 28% | 16% |
| September 22 | 69°F | 46°F | 28% | 16% |
| September 30 | 65°F | 43°F | 26% | 14% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 77°F | 54°F | 28% | 15% | 13 h 20 min |
| September 2 | 76°F | 54°F | 28% | 15% | 13 h 20 min |
| September 3 | 76°F | 53°F | 28% | 15% | 13 h 10 min |
| September 4 | 76°F | 53°F | 28% | 15% | 13 h 10 min |
| September 5 | 76°F | 53°F | 28% | 15% | 13 h 10 min |
| September 6 | 75°F | 52°F | 28% | 16% | 13 h |
| September 7 | 75°F | 52°F | 28% | 16% | 13 h |
| September 8 | 75°F | 52°F | 28% | 16% | 13 h |
| September 9 | 74°F | 51°F | 28% | 16% | 12 h 50 min |
| September 10 | 74°F | 51°F | 28% | 16% | 12 h 50 min |
| September 11 | 74°F | 51°F | 28% | 16% | 12 h 50 min |
| September 12 | 73°F | 50°F | 28% | 16% | 12 h 50 min |
| September 13 | 73°F | 50°F | 28% | 16% | 12 h 40 min |
| September 14 | 73°F | 49°F | 28% | 16% | 12 h 40 min |
| September 15 | 72°F | 49°F | 28% | 16% | 12 h 40 min |
| September 16 | 72°F | 49°F | 28% | 16% | 12 h 30 min |
| September 17 | 71°F | 48°F | 28% | 16% | 12 h 30 min |
| September 18 | 71°F | 48°F | 28% | 16% | 12 h 30 min |
| September 19 | 71°F | 47°F | 28% | 16% | 12 h 20 min |
| September 20 | 70°F | 47°F | 28% | 16% | 12 h 20 min |
| September 21 | 70°F | 47°F | 28% | 16% | 12 h 20 min |
| September 22 | 69°F | 46°F | 28% | 16% | 12 h 10 min |
| September 23 | 69°F | 46°F | 28% | 15% | 12 h 10 min |
| September 24 | 68°F | 45°F | 28% | 15% | 12 h 10 min |
| September 25 | 68°F | 45°F | 27% | 15% | 12 h 10 min |
| September 26 | 67°F | 44°F | 27% | 15% | 12 h |
| September 27 | 67°F | 44°F | 27% | 15% | 12 h |
| September 28 | 66°F | 43°F | 27% | 15% | 12 h |
| September 29 | 66°F | 43°F | 27% | 14% | 11 h 50 min |
| September 30 | 65°F | 43°F | 26% | 14% | 11 h 50 min |
- Normal high
- 72°FSeptember average
- Normal low
- 49°FSeptember average
- Precipitation
- 2.45 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 1
- Nights at 32°F or colder
- 1
- Daylight
- 13 h 20 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 18
- Days at 80°F or more
- 8
- Sunshine
- 79%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014946; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Watertown in September?
On a given September day the chance of 0.01 inch or more is 28% on average, highest around September 12 (28%). In all, 2.45 in falls on 9 days of a normal September, 1 of them with an inch or more.
In a normal September in Watertown, 1 days reach 90°F and 1 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014946.
How humid and windy is Watertown in September?
At 3 p.m. the normal temperature is 63°F with 47% relative humidity and a dew point of 43°F; at 6 a.m. it is 46°F with 84% humidity. The wind averages 10.5 mph, most often from the west in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 46°F | 41°F | 84% | 8.8 mph | 71% |
| 9 a.m. | 52°F | 44°F | 72% | 11.8 mph | 70% |
| noon | 60°F | 43°F | 52% | 13.8 mph | 73% |
| 3 p.m. | 63°F | 43°F | 47% | 13.7 mph | 66% |
| 6 p.m. | 58°F | 43°F | 56% | 10.0 mph | 70% |
| 9 p.m. | 52°F | 43°F | 71% | 8.6 mph | 71% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014946. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Watertown?
The warmest September temperature on this station's record (since 1893) is 104°F, on September 10, 1931; the coldest is 9°F, on September 29, 1899. The wettest September brought 7.22 in (1921); the snowiest, 1.2 inches (1942).
The September mean against the 1991-2020 normal of 60.1°F: 2021 63.3°F (+3.2), 2022 63.3°F (+3.2), 2023 65.5°F (+5.4), 2024 66.1°F (+6.0), 2025 64.5°F (+4.4), 2026 65.1°F (+5.0). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 63.3°F | +3.2°F | 3.01 in |
| 2022 | 63.3°F | +3.2°F | 1.02 in |
| 2023 | 65.5°F | +5.4°F | 2.74 in |
| 2024 | 66.1°F | +6.0°F | 0.25 in |
| 2025 | 64.5°F | +4.4°F | 1.55 in |
| 2026 | 65.1°F | +5.0°F | 3.61 in |
Source: records: ACIS, station USW00014946; recent months: ACIS, station USW00014946. Records and recent months use complete months only.
How does September in Watertown compare across South Dakota?
Across the 100 places PlainClimate covers in South Dakota, September normal highs run from 69°F in Custer to 82°F in Interior; Watertown's is 72°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Watertown in August80°F by day, 58°F at night
- Watertown in October56°F by day, 35°F at night
- Watertown through the yearEvery month, frost dates, records and recent years
- South Dakota in SeptemberThe statewide normal and the warmest and coolest places
- Interior: South Dakota's warmest Septembernormal high 82°F