Jefferson, SD Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Jefferson, a city in Union County, South Dakota.
Today
69°F
Patchy Smoke
Patchy smoke and showers and thunderstorms before 3pm, then scattered showers and thunderstorms between 3pm and 4pm, then patchy smoke and scattered showers and thunderstorms. Mostly cloudy, with a high near 69. North northwest wind 5 to 10 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast for Jefferson
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 69°F | Patchy Smoke | 5 to 10 mph NNW | 82% |
| Tonight | 56°F | Patchy Smoke then Mostly Cloudy | 0 to 5 mph NNE | 47% |
| Wednesday | 76°F | Partly Sunny | 0 to 5 mph E | 4% |
| Wednesday Night | 54°F | Mostly Clear | 0 to 5 mph SSE | 1% |
| Thursday | 82°F | Mostly Sunny | 0 to 10 mph S | 0% |
| Thursday Night | 62°F | Mostly Clear | 5 to 10 mph S | 2% |
| Friday | 87°F | Sunny | 5 to 10 mph SSW | 3% |
| Friday Night | 66°F | Mostly Clear | 5 to 10 mph S | 10% |
| Saturday | 91°F | Sunny | 5 to 15 mph S | 4% |
| Saturday Night | 69°F | Mostly Clear | 10 to 15 mph SSE | 14% |
| Sunday | 90°F | Mostly Sunny | 10 to 15 mph SE | 13% |
| Sunday Night | 69°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 10 to 15 mph ESE | 16% |
| Monday | 90°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 10 to 15 mph E | 16% |
| Monday Night | 69°F | Slight Chance Showers And Thunderstorms | 10 to 15 mph E | 22% |
Forecast source: National Weather Service (api.weather.gov) for Jefferson (42.604, -96.566). Updated through the day.
Growing snapshot for Jefferson
Last spring frost
Apr 29
First fall frost
Oct 7
Growing season
161 days
Hardiness zone
5a
More local growing data for Jefferson: nearby ZIP 57038 weather · frost dates · planting calendar · South Dakota frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Sioux City Ang, Ia (16.1 mi from Jefferson). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.