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Frost Dates in South Dakota
First and last frost dates across South Dakota, computed from 92 NOAA weather stations (1991–2020 climate normals). Your exact date depends on your city and microclimate — use the ZIP lookup on the main tool for a station-specific answer.
Last spring frost
May 8
statewide median · range Apr 27–Jun 1
First fall frost
Oct 1
statewide median · range Sep 10–Oct 13
Growing season
145 days
median · range 102–165
Stations used
92
NOAA 1991–2020 normals
Frost dates by city
Median dates from the nearest NOAA station to each city. The "cautious" date is the 10% spring value — planting after it means only a ~10% chance of a later frost.
| City | Nearest station | Last spring frost | First fall frost | Growing season | Safe transplant |
|---|---|---|---|---|---|
| Sioux Falls | Sioux Falls · 3 mi | May 1 (cautious: May 14) | Oct 6 | 157 days | May 15 |
| Rapid City | Rapid City Rgnl Ap · 9 mi | May 12 (cautious: May 26) | Oct 1 | 139 days | May 26 |
| Aberdeen | Aberdeen · 4 mi | May 9 (cautious: May 22) | Sep 26 | 139 days | May 23 |
How frost varies across South Dakota
Spring frost timing spans about 35 days across the state. Yankton Chan Gurney Muni in southeastern South Dakota typically sees its last spring frost around April 27, while Hill City in western South Dakota doesn't clear frost until about June 1. Within any city, low spots and valleys run colder than the station average; areas near buildings and pavement run warmer.
When to plant in South Dakota
As a rule of thumb, cool-season crops (lettuce, peas, spinach) can go in 2–4 weeks before your last spring frost; warm-season transplants (tomatoes, peppers) should wait about 2 weeks after it — around May 22 for the statewide median. Check your city's row above rather than the statewide median: a 35-day statewide spread makes the city-level date the one that matters.
These are climate normals (what's typical), not forecasts. For the current year, watch the 10-day forecast around your planting date.
How this is computed
Statewide medians are the median of the 92 NOAA stations' median frost dates — half the stations run earlier, half later. City rows use the nearest station with 30-year freeze records. Dates are 32°F freeze probabilities from NOAA NCEI 1991–2020 U.S. Climate Normals; nothing is estimated or interpolated.
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Frequently asked questions
When is the last frost date in South Dakota?
The statewide median last spring frost is May 8, but it ranges from April 27 to June 1 depending on where in the state you are. Use your city's row in the table above, or the ZIP lookup on the main tool, for a station-specific date.
When can I plant tomatoes outside in South Dakota?
Warm-season transplants like tomatoes should wait about two weeks after your last spring frost — around May 22 for the statewide median. Your city may differ by weeks; check the "safe transplant" column in the city table.
How long is the growing season in South Dakota?
The median growing season across 92 NOAA stations is 145 days, ranging from 102 to 165 days by location.
Why do frost dates vary so much within South Dakota?
Frost timing follows latitude, elevation, and local terrain. Across South Dakota, last spring frost dates span about 35 days — from around April 27 near Yankton Chan Gurney Muni to June 1 near Hill City. Microclimates (low spots, valleys, urban heat) shift dates further at the garden level.
Where does this data come from?
All frost dates are computed from the NOAA National Centers for Environmental Information 1991–2020 U.S. Climate Normals freeze data (public domain), using each station's 32°F freeze probability statistics. No dates are estimated or interpolated.