Last frost date in Rapid City, SD

Average last frost
May 3

The average last frost in Rapid City is May 3. By May 17 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 8, which leaves 157 frost-free days. An early freeze before September 26 happens one year in ten.

Safe after (10% risk)
May 17
Average first frost
Oct 8
Frost-free season
157 days
Hard freeze (28°F) ends
Apr 22
Next 7 nights in Rapid City

Frost possible in low spots Sun night, low 34°F

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2256°
  2. FriOct 2343°
  3. SatOct 2437°
  4. SunOct 2534°possible frost
  5. MonOct 2633°possible frost
  6. TueOct 2737°
  7. WedOct 2837°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 3First frost Oct 8157 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND157 frost-free days
Frost risk through the year at Rapid City Wfo, 0.4 miles from Rapid City.

Planting calendar for Rapid City

Windows count forward or back from the average frost dates above. Click a crop for dates across South Dakota.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 10–May 24
PumpkinsMay 17–May 31
SunflowersMay 3–May 24
CucumbersMay 17–May 24
CornMay 10–May 24
Sweet potatoesMay 24–Jun 7
WatermelonMay 17–May 31
Green beansMay 10–May 31
ZucchiniMay 10–May 24
OkraMay 24–Jun 7
PeppersMay 17–May 31
BasilMay 10–May 24
Butternut squashMay 10–May 24
CantaloupeMay 17–May 31
EggplantMay 17–May 31
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 5–Apr 19
OnionsMar 22–Apr 12
CarrotsApr 12–May 17
LettuceApr 19–May 10
BroccoliApr 5–Apr 19
BeetsApr 5–May 17
PeasMar 22–Apr 5
CabbageApr 5–Apr 19
RadishesMar 29–May 10
Brussels sproutsApr 19–May 3
SpinachMar 22–Apr 12
CilantroApr 19–May 10
KaleApr 5–Apr 19
Collard greensApr 5–Apr 19
TurnipsApr 5–Apr 19
DillMay 3–May 17
CeleryMay 10–May 17
CauliflowerApr 19–May 3
LeeksApr 19–May 3
Swiss chardApr 19–May 17
ParsleyApr 19–May 10
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 24–Oct 29
GarlicSep 17–Oct 22
Daffodil bulbsSep 10–Oct 22
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 5–Apr 19
AsparagusApr 5–Apr 19

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 20May 3May 17Sep 26Oct 8Oct 23
Hard freeze, 28°FApr 8Apr 22May 5Oct 3Oct 18Nov 1

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Rapid City Wfo (USC00396948) sits 0.4 miles from the center of Rapid City at 3,379 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Rapid City, SD?

The average last frost date in Rapid City is May 3, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 17.

When is the first frost in Rapid City?

The first frost in fall usually comes around October 8. One year in ten it arrives before September 26.

How long is the growing season in Rapid City?

About 157 days between the average last and first frost.

When should I plant tomatoes in Rapid City?

Plant tomato seedlings outside from May 10 to May 24. Start seeds indoors six to eight weeks earlier.

Nearby in South Dakota

All 5 cities in South Dakota