Last frost dates in South Dakota
166 NOAA weather stations in South Dakota have thirty years of frost records. The median station sees its last 32 °F night around May 8; across the state that ranges from Apr 26 to Jun 1, so pick the station nearest you rather than a state-wide figure.
| SIOUX FALLS WFO AP | Apr 26 | May 9 | Apr 10 | Oct 13 | 169 |
| MITCHELL | Apr 27 | May 10 | Apr 12 | Oct 11 | 167 |
| PICKSTOWN 4SSW | Apr 27 | May 11 | Apr 14 | Oct 13 | 168 |
| YANKTON 2 E | Apr 27 | May 10 | Apr 13 | Oct 11 | 164 |
| WAGNER | Apr 29 | May 12 | Apr 12 | Oct 9 | 164 |
| ACADEMY 2NE | Apr 30 | May 14 | Apr 16 | Oct 8 | 159 |
| BRIDGEWATER | Apr 30 | May 11 | Apr 15 | Oct 7 | 161 |
| MITCHELL MUNI AP | Apr 30 | May 13 | Apr 16 | Oct 5 | 159 |
| PICKSTOWN | Apr 30 | May 12 | Apr 17 | Oct 13 | 165 |
| CHAMBERLAIN MUNI AP | May 1 | May 14 | Apr 18 | Oct 7 | 158 |
| MENNO | May 1 | May 14 | Apr 17 | Oct 4 | 156 |
| SIOUX FALLS | May 1 | May 14 | Apr 18 | Oct 6 | 157 |
| SIOUX FALLS 14 NNE | May 1 | May 15 | Apr 16 | Oct 4 | 155 |
| TYNDALL | May 1 | May 14 | Apr 18 | Oct 7 | 158 |
| WAUBAY NATL WILD LIFE | May 1 | May 12 | Apr 17 | Oct 12 | 164 |
| WINNER | May 1 | May 16 | Apr 17 | Oct 9 | 159 |
| WINNER WILEY FLD | May 1 | May 15 | Apr 16 | Oct 10 | 162 |
| CANTON | May 2 | May 15 | Apr 19 | Oct 2 | 151 |
| CENTERVILLE 6 SE | May 2 | May 15 | Apr 19 | Oct 1 | 151 |
| MILBANK 4 NW | May 2 | May 15 | Apr 20 | Oct 4 | 153 |
| MITCHELL 2 N | May 2 | May 15 | Apr 19 | Oct 6 | 156 |
| ROY LAKE | May 2 | May 15 | Apr 19 | Oct 9 | 160 |
| WENTWORTH 2.5 WNW | May 2 | May 14 | Apr 18 | Oct 5 | 156 |
| WESSINGTON SPRINGS | May 2 | May 14 | Apr 20 | Oct 8 | 157 |
| ARLINGTON 1 W | May 3 | May 15 | Apr 21 | Oct 2 | 151 |
| ARMOUR | May 3 | May 18 | Apr 17 | Oct 6 | 157 |
| BONESTEEL | May 3 | May 15 | Apr 19 | Oct 10 | 159 |
| CHAMBERLAIN 5 S | May 3 | May 17 | Apr 19 | Oct 7 | 156 |
| MILLER | May 3 | May 16 | Apr 19 | Oct 3 | 152 |
| MOBRIDGE 2NNW | May 3 | May 16 | Apr 20 | Oct 8 | 157 |
| MONTROSE 8N | May 3 | May 15 | Apr 20 | Oct 4 | 153 |
| MURDO | May 3 | May 16 | Apr 19 | Oct 9 | 158 |
| RAPID CITY WFO | May 3 | May 17 | Apr 20 | Oct 8 | 157 |
| SISSETON MUNI AP | May 3 | May 16 | Apr 21 | Sep 30 | 149 |
| VERMILLION 2 SE | May 3 | May 16 | Apr 20 | Oct 3 | 153 |
| WATERTOWN 2 S | May 3 | May 14 | Apr 20 | Oct 4 | 153 |
| WHITE LAKE | May 3 | May 17 | Apr 20 | Oct 5 | 153 |
| SISSETON | May 4 | May 17 | Apr 21 | Oct 3 | 151 |
| VICTOR 4 N | May 4 | May 17 | Apr 21 | Oct 3 | 152 |
| WEBSTER | May 4 | May 16 | Apr 20 | Oct 6 | 156 |
| CLARK | May 5 | May 18 | Apr 22 | Oct 5 | 153 |
| CLARK NO2 | May 5 | May 17 | Apr 22 | Oct 5 | 152 |
| DE SMET | May 5 | May 20 | Apr 22 | Oct 4 | 151 |
| FLANDREAU | May 5 | May 17 | Apr 23 | Oct 1 | 148 |
| HOWARD | May 5 | May 18 | Apr 24 | Oct 2 | 149 |
| INTERIOR 3 NE | May 5 | May 20 | Apr 22 | Oct 7 | 152 |
| MADISON 2SE | May 5 | May 18 | Apr 22 | Sep 30 | 148 |
| MILBANK | May 5 | May 18 | Apr 22 | Oct 2 | 150 |
| MOBRIDGE MUNI AP | May 5 | May 20 | Apr 23 | Oct 4 | 150 |
| WILMOT | May 5 | May 18 | Apr 24 | Oct 1 | 149 |
| ANDOVER #2 | May 6 | May 21 | Apr 22 | Oct 4 | 150 |
| ASTORIA 4S | May 6 | May 20 | Apr 23 | Oct 3 | 150 |
| BROOKINGS 2 NE | May 6 | May 19 | Apr 25 | Oct 1 | 145 |
| CASTLEWOOD #2 | May 6 | May 20 | Apr 25 | Oct 1 | 145 |
| CEDAR BUTTE | May 6 | May 22 | Apr 24 | Oct 4 | 151 |
| CONDE | May 6 | May 20 | Apr 25 | Sep 29 | 144 |
| DUPREE 15 SSE | May 6 | May 20 | Apr 24 | Oct 2 | 148 |
| FAITH | May 6 | May 20 | Apr 23 | Oct 5 | 151 |
| GANN VALLEY 4NW | May 6 | May 19 | Apr 23 | Oct 1 | 148 |
| GREGORY | May 6 | May 20 | Apr 23 | Oct 3 | 149 |
| HURON RGNL AP | May 6 | May 20 | Apr 23 | Oct 2 | 146 |
| KIRLEY 6 N | May 6 | May 21 | Apr 24 | Oct 4 | 148 |
| LAKE SHARPE PRJ | May 6 | May 20 | Apr 25 | Oct 5 | 152 |
| MISSION RIDGE 5NW | May 6 | May 22 | Apr 23 | Oct 7 | 152 |
| OAHE DAM | May 6 | May 19 | Apr 23 | Oct 5 | 152 |
| PIERRE 24 S | May 6 | May 20 | Apr 23 | Oct 7 | 154 |
| PIERRE RGNL AP | May 6 | May 21 | Apr 24 | Oct 3 | 148 |
| WINFRED 2S | May 6 | May 17 | Apr 23 | Oct 3 | 151 |
| CLEAR LAKE | May 7 | May 21 | Apr 25 | Oct 1 | 146 |
| COLUMBIA 8 N | May 7 | May 22 | Apr 26 | Sep 29 | 145 |
| FAITH MUNI AP | May 7 | May 20 | Apr 25 | Oct 3 | 147 |
| GANN VALLEY 3 NNE | May 7 | May 21 | Apr 25 | Oct 1 | 146 |
| GETTYSBURG | May 7 | May 21 | Apr 24 | Oct 2 | 147 |
| OGLALA 1S | May 7 | May 21 | Apr 24 | Oct 4 | 149 |
| RAUVILLE 2 W | May 7 | May 20 | Apr 24 | Sep 28 | 143 |
| ROSCOE | May 7 | May 20 | Apr 24 | Oct 3 | 148 |
| SALEM 5NE | May 7 | May 19 | Apr 25 | Sep 29 | 144 |
| TURTON | May 7 | May 22 | Apr 23 | Oct 3 | 149 |
| WATERTOWN RGNL AP | May 7 | May 20 | Apr 26 | Sep 30 | 145 |
| ABERDEEN 3 E | May 8 | May 21 | Apr 25 | Sep 29 | 144 |
| ALEXANDRIA | May 8 | May 21 | Apr 27 | Sep 29 | 143 |
| DUPREE | May 8 | May 22 | Apr 26 | Oct 1 | 144 |
| ELM SPRINGS 3 ESE | May 8 | May 22 | Apr 27 | Oct 3 | 146 |
| FT MEADE | May 8 | May 21 | Apr 26 | Oct 3 | 147 |
| HEREFORD 12 SW | May 8 | May 22 | Apr 27 | Oct 3 | 147 |
| IPSWICH | May 8 | May 22 | Apr 26 | Sep 29 | 143 |
| MILESVILLE 5 NE | May 8 | May 22 | Apr 27 | Oct 2 | 147 |
| NEWELL | May 8 | May 22 | Apr 27 | Oct 1 | 144 |
| ONIDA 4 NW | May 8 | May 22 | Apr 25 | Oct 2 | 147 |
| POLLOCK | May 8 | May 21 | Apr 27 | Sep 30 | 143 |
| REDFIELD | May 8 | May 21 | Apr 25 | Oct 1 | 145 |
| SELBY | May 8 | May 21 | Apr 26 | Oct 1 | 145 |
| ABERDEEN | May 9 | May 22 | Apr 27 | Sep 26 | 139 |
| FORESTBURG 4 NNE | May 9 | May 24 | Apr 27 | Sep 28 | 140 |
| LEOLA | May 9 | May 21 | Apr 28 | Sep 28 | 141 |
| LONGVALLEY | May 9 | May 24 | Apr 26 | Oct 1 | 143 |
| MANDERSON 3 NE | May 9 | May 24 | Apr 27 | Oct 4 | 147 |
| MC INTOSH 6 SE | May 9 | May 24 | Apr 28 | Sep 30 | 143 |
| MISSION | May 9 | May 21 | Apr 28 | Oct 1 | 146 |
| ABERDEEN 35 WNW | May 10 | May 22 | Apr 28 | Sep 30 | 143 |
| BELLE FOURCHE | May 10 | May 25 | Apr 27 | Sep 30 | 143 |
| BISON | May 10 | May 24 | Apr 30 | Oct 1 | 144 |
| BUFFALO ASOS | May 10 | May 23 | Apr 30 | Oct 1 | 141 |
| CASTLEWOOD | May 10 | May 23 | Apr 29 | Sep 27 | 139 |
| FAULKTON 1 NW | May 10 | May 25 | Apr 29 | Sep 28 | 139 |
| FT PIERRE 17 WSW | May 10 | May 25 | Apr 29 | Sep 27 | 138 |
| LEMMON | May 10 | May 24 | Apr 30 | Sep 30 | 142 |
| RAPID CITY 4NW | May 10 | May 25 | Apr 27 | Oct 5 | 147 |
| STEPHAN 2 NW | May 10 | May 24 | Apr 29 | Sep 29 | 140 |
| TIMBER LAKE | May 10 | May 23 | Apr 29 | Sep 30 | 141 |
| WASTA | May 10 | May 25 | Apr 30 | Oct 1 | 141 |
| WOOD | May 10 | May 22 | Apr 27 | Oct 1 | 143 |
| GLAD VALLEY 2 W | May 11 | May 24 | Apr 30 | Sep 30 | 140 |
| HARRINGTON | May 11 | May 24 | Apr 29 | Oct 1 | 143 |
| KYLE 2 E | May 11 | May 27 | Apr 29 | Oct 1 | 139 |
| MELLETTE 4 W | May 11 | May 23 | Apr 29 | Sep 27 | 137 |
| MISSION 14 S | May 11 | May 25 | Apr 30 | Oct 2 | 145 |
| PHILIP AP | May 11 | May 24 | Apr 29 | Sep 30 | 141 |
| ZEONA 10 SSW | May 11 | May 27 | Apr 30 | Sep 28 | 137 |
| EUREKA | May 12 | May 25 | May 1 | Sep 27 | 137 |
| HIGHMORE 1 W | May 12 | May 28 | Apr 28 | Oct 1 | 142 |
| KENNEBEC | May 12 | May 26 | Apr 29 | Sep 28 | 137 |
| MC LAUGHLIN | May 12 | May 25 | May 2 | Sep 28 | 137 |
| MIDLAND | May 12 | May 26 | Apr 30 | Sep 28 | 138 |
| PRESHO 7 NW | May 12 | May 28 | Apr 29 | Sep 29 | 140 |
| RAPID CITY RGNL AP | May 12 | May 26 | May 1 | Oct 1 | 139 |
| SPEARFISH | May 12 | May 25 | Apr 29 | Oct 2 | 143 |
| BRITTON | May 13 | May 27 | Apr 29 | Sep 26 | 135 |
| LADNER 9SW | May 13 | May 25 | May 2 | Sep 27 | 135 |
| MARTIN | May 13 | May 27 | Apr 30 | Oct 2 | 141 |
| MAURINE 12SW | May 13 | May 27 | May 2 | Sep 28 | 136 |
| HIGHMORE 23 N | May 14 | May 25 | Apr 30 | Sep 29 | 138 |
| MARTIN 8 E | May 14 | May 28 | May 3 | Oct 1 | 139 |
| SUMMIT 1 W | May 14 | May 28 | May 1 | Sep 28 | 136 |
| BELLE FOURCHE 22 NNW | May 15 | May 28 | May 4 | Sep 24 | 130 |
| MT RUSHMORE NMEM | May 15 | May 29 | May 1 | Oct 1 | 138 |
| OELRICHS | May 15 | May 28 | May 4 | Sep 30 | 137 |
| ORAL | May 15 | May 28 | May 5 | Sep 27 | 133 |
| PLAINVIEW 6 SSW | May 15 | May 29 | May 3 | Sep 27 | 134 |
| REDIG 11 NE | May 15 | May 27 | May 3 | Sep 24 | 131 |
| WIND CAVE | May 15 | May 30 | May 4 | Sep 29 | 133 |
| ARDMORE 1 NW | May 16 | May 31 | May 3 | Sep 23 | 128 |
| COTTONWOOD 2 E | May 16 | May 29 | May 4 | Sep 26 | 132 |
| HOT SPRINGS | May 16 | May 31 | May 4 | Sep 27 | 133 |
| LUDLOW 3 SSE | May 16 | May 29 | May 4 | Sep 26 | 131 |
| PINE RIDGE AP | May 16 | May 31 | May 3 | Sep 27 | 132 |
| RED OWL | May 16 | May 27 | May 4 | Sep 26 | 131 |
| SHADEHILL RSVR | May 16 | May 29 | May 6 | Sep 24 | 131 |
| BEAR RIDGE | May 17 | May 30 | May 5 | Sep 27 | 132 |
| CAMP CROOK | May 17 | May 30 | May 4 | Sep 24 | 128 |
| HARROLD 12 SSW | May 17 | May 31 | May 4 | Sep 24 | 129 |
| PORCUPINE 11 N | May 17 | Jun 1 | May 3 | Sep 25 | 130 |
| CUSTER | May 18 | Jun 1 | May 5 | Sep 28 | 129 |
| EDGEMONT 23 NNW | May 18 | Jun 1 | May 4 | Sep 27 | 130 |
| LEAD | May 18 | Jun 1 | May 5 | Sep 29 | 133 |
| RALPH 1 N | May 18 | May 31 | May 7 | Sep 23 | 126 |
| ANTELOPE RS | May 19 | Jun 2 | May 7 | Sep 19 | 121 |
| HOOVER | May 19 | May 31 | May 7 | Sep 21 | 122 |
| BUFFALO 13 ESE | May 20 | Jun 2 | May 8 | Sep 19 | 120 |
| JOHNSON SIDING | May 20 | Jun 3 | May 9 | Sep 25 | 126 |
| CUSTER CO AP | May 23 | Jun 6 | May 10 | Sep 24 | 122 |
| EDGEMONT | May 23 | Jun 7 | May 11 | Sep 20 | 117 |
| DEADWOOD | May 24 | Jun 6 | May 7 | Sep 25 | 125 |
| PACTOLA DAM | May 28 | Jun 11 | May 16 | Sep 18 | 112 |
| LODGEPOLE 5SW | May 30 | Jun 13 | May 18 | Sep 11 | 103 |
| HILL CITY | Jun 1 | Jun 19 | May 18 | Sep 10 | 102 |
How to read the three dates
Average is the date by which, in half of the years between 1991 and 2020, the last 32 °F night had already happened. Safe is later: only one year in ten saw a frost after it, which is the date to set out frost-tender plants such as dahlia tubers and zinnia seedlings. Early is the risky end, with a frost after it in nine years out of ten.
Every figure is for the weather station, not for your garden. A valley bottom, a north slope or a spot near a lake can run a week or two either way. Cities are warmer than the countryside around them.
Where the numbers come from
The dates are NOAA's U.S. Climate Normals for 1991 to 2020, computed by the National Centers for Environmental Information for every station with thirty years of daily minimum temperatures. ZIP codes are matched to the nearest such station within 150 km using U.S. Census Bureau ZIP Code Tabulation Area centroids. Stations that never see a frost, such as much of south Florida, report no date and are left out.