Sioux Falls
Treat broadleaf54°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 2 – Oct 23
South Dakota Weed Watch · updated Nov 3, 1:18 AM CT
When to apply pre-emergent in South Dakota
Live soil temperatures for Sioux Falls, Rapid City and Aberdeen, updated every three hours. Weeds sprout by soil temperature, not by the calendar, so the right week moves from year to year.
In South Dakota, pre-emergent is a spring job: it stops crabgrass. Fall is seeding season here, so fall weed control means treating broadleaf weeds instead.
Spring pre-emergentNext season
Typically Apr 17 – May 13
Stops crabgrass and other summer weeds before they sprout.
Fall: no pre-emergentThis season
Treat broadleaf weeds Sep 1 – Oct 23
Fall is seeding season here, and pre-emergent would stop grass seed too.
Right now · fall (seeding season)
Treat broadleaf weeds now across South Dakota
Soil is 50–54°F now. In fall, dandelions, clover and creeping Charlie pull sugars — and weed killer — down to their roots. Seeding this fall? Skip pre-emergent; it stops grass seed too.
Soil temperature by city
Soil 2 inches down, 5-day average: solid line = the last two weeks, dashed = the six-day forecast.
Rapid City
Treat broadleaf50°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 4 – Oct 22
Aberdeen
Treat broadleaf52°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 1 – Oct 21
South Dakota pre-emergent calendar
Spring pre-emergent stops crabgrass. The window runs from the typical day soil warms to 50°F to the day it holds 55°F, when crabgrass starts germinating (2016–2025). In fall South Dakota lawns are in seeding season, so there is no fall pre-emergent; the window shown is for treating broadleaf weeds instead, from September until two weeks after soil usually cools to 55°F.
| City | Spring pre-emergent (crabgrass) | Fall (seeding season) |
|---|---|---|
| Sioux Falls | Apr 17 – May 6 | None (seeding season) · treat broadleaf Sep 2 – Oct 23 |
| Rapid City | Apr 28 – May 13 | None (seeding season) · treat broadleaf Sep 4 – Oct 22 |
| Aberdeen | May 2 – May 12 | None (seeding season) · treat broadleaf Sep 1 – Oct 21 |
These are typical-year dates (the median of 2016–2025); any one year can run a couple of weeks earlier or later, which is what the live readings above are for. For your exact yard, check soil temperature by ZIP.
What people in South Dakota are identifying
We record the state each identification comes from. South Dakota's list appears here once it has at least 40 identifications spread over 7 or more days — so no single scan stands out. Until then, see the national list, or add yours:
Identify a weed from a photoWeeds to watch in South Dakota this fall
Questions about South Dakota
When should I apply crabgrass pre-emergent in South Dakota?
Put crabgrass pre-emergent down as soil warms to 50°F, before it holds 55°F and crabgrass starts germinating. In a typical year (2016–2025) that window is Apr 17 – May 6 in Sioux Falls; Apr 28 – May 13 in Rapid City; May 2 – May 12 in Aberdeen.
Should I put down pre-emergent in the fall in South Dakota?
Usually not. Fall is the best time to seed a cool-season lawn in South Dakota, and pre-emergent stops grass seed as well as weeds. Fall is the time to treat broadleaf weeds such as dandelion, clover and creeping Charlie, once the summer heat breaks and while they are still growing.
What is the soil temperature in South Dakota right now?
As of Nov 3, 1:18 AM CT: Sioux Falls 54°F, Rapid City 50°F, Aberdeen 52°F (5-day average, about 2.4 inches down). Treat broadleaf weeds now across South Dakota.
How the readings and dates are made, and their limits: Weed Watch method. Soil data: Open-Meteo.com (CC BY 4.0); typical dates: NASA POWER.