Jefferson, SD Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Jefferson, a city in Union County, South Dakota.
Tonight
39°F
Rain Showers
Rain showers before 5am. Cloudy. Low around 39, with temperatures rising to around 42 overnight. Northwest wind around 15 mph, with gusts as high as 25 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 |
|---|---|---|---|---|
| Tonight | 39°F | Rain Showers | 15 mph NW | 75% |
| Wednesday | 48°F | Chance Rain Showers | 15 to 20 mph NW | 46% |
| Wednesday Night | 37°F | Rain Showers Likely | 10 to 15 mph NW | 55% |
| Thursday | 50°F | Slight Chance Rain Showers then Mostly Cloudy | 10 to 15 mph NNW | 19% |
| Thursday Night | 33°F | Mostly Cloudy | 5 to 10 mph N | 0% |
| Friday | 50°F | Partly Sunny | 0 to 5 mph ENE | 0% |
| Friday Night | 32°F | Mostly Cloudy | 0 mph | 1% |
| Saturday | 59°F | Mostly Sunny | 0 to 5 mph SW | 2% |
| Saturday Night | 35°F | Mostly Clear | 5 mph W | 5% |
| Sunday | 61°F | Sunny | 5 mph WSW | 2% |
| Sunday Night | 39°F | Mostly Clear | 5 mph S | 0% |
| Monday | 64°F | Sunny | 5 to 10 mph WSW | 0% |
| Monday Night | 38°F | Mostly Clear | 5 mph NW | 0% |
| Tuesday | 61°F | Mostly Sunny | 5 mph SW | 0% |
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 Nov 4, 2026.