Last frost dates in Montana
216 NOAA weather stations in Montana have thirty years of frost records. The median station sees its last 32 °F night around May 20; across the state that ranges from Apr 30 to Jun 18, so pick the station nearest you rather than a state-wide figure.
| Plan sowing from this date | ||||||
|---|---|---|---|---|---|---|
| NORRIS MADISON PWR HOUSE | Apr 30 | May 14 | Apr 15 | Oct 10 | 162 | Plan sowing from this date → |
| BIGFORK 13 S | May 1 | May 16 | Apr 16 | Oct 15 | 165 | Plan sowing from this date → |
| GLASGOW #2 | May 3 | May 15 | Apr 19 | Oct 1 | 151 | Plan sowing from this date → |
| GLENDIVE | May 3 | May 16 | Apr 19 | Oct 4 | 153 | Plan sowing from this date → |
| BILLINGS LOGAN INTL AP | May 4 | May 18 | Apr 20 | Oct 7 | 156 | Plan sowing from this date → |
| BILLINGS WFO | May 5 | May 21 | Apr 23 | Oct 3 | 149 | Plan sowing from this date → |
| MOSBY 4 ENE | May 5 | May 26 | Apr 20 | Oct 4 | 151 | Plan sowing from this date → |
| GLASGOW INTL AP | May 6 | May 18 | Apr 24 | Sep 30 | 145 | Plan sowing from this date → |
| GREAT FALLS 16ST | May 6 | May 19 | Apr 23 | Oct 1 | 147 | Plan sowing from this date → |
| MISSOULA 6 NW WFO | May 6 | May 19 | Apr 24 | Oct 4 | 151 | Plan sowing from this date → |
| HIGHWOOD 7 NE | May 7 | May 21 | Apr 24 | Oct 2 | 149 | Plan sowing from this date → |
| MALTA 7 E | May 7 | May 21 | Apr 24 | Sep 28 | 143 | Plan sowing from this date → |
| THOMPSON FALLS PH | May 7 | May 19 | Apr 25 | Oct 4 | 150 | Plan sowing from this date → |
| YELLOWTAIL DAM | May 7 | May 24 | Apr 20 | Oct 5 | 151 | Plan sowing from this date → |
| FT PECK PWR PLT | May 8 | May 20 | Apr 25 | Oct 1 | 145 | Plan sowing from this date → |
| MILES CITY F WILEY FLD | May 8 | May 21 | Apr 26 | Sep 30 | 144 | Plan sowing from this date → |
| WOLF PT | May 8 | May 20 | Apr 25 | Sep 28 | 143 | Plan sowing from this date → |
| FORSYTH | May 9 | May 21 | Apr 28 | Sep 29 | 142 | Plan sowing from this date → |
| HELENA RGNL AP | May 9 | May 25 | Apr 29 | Sep 30 | 142 | Plan sowing from this date → |
| HUNGRY HORSE DAM | May 9 | May 30 | Apr 25 | Oct 1 | 141 | Plan sowing from this date → |
| TRIDENT | May 9 | May 24 | Apr 29 | Sep 27 | 139 | Plan sowing from this date → |
| BILLINGS WTP | May 10 | May 24 | Apr 26 | Oct 1 | 142 | Plan sowing from this date → |
| HYSHAM | May 10 | May 22 | Apr 28 | Sep 29 | 141 | Plan sowing from this date → |
| LIBBY | May 10 | May 26 | Apr 28 | Sep 26 | 137 | Plan sowing from this date → |
| MALTA | May 10 | May 22 | Apr 29 | Sep 29 | 139 | Plan sowing from this date → |
| MELSTONE | May 10 | May 23 | Apr 28 | Sep 29 | 141 | Plan sowing from this date → |
| MISSOULA 2 NE | May 10 | May 28 | Apr 27 | Oct 1 | 143 | Plan sowing from this date → |
| POLSON | May 10 | May 26 | Apr 27 | Oct 5 | 147 | Plan sowing from this date → |
| EUREKA RS | May 11 | May 25 | Apr 28 | Sep 27 | 138 | Plan sowing from this date → |
| LIBBY DAM (BASE) | May 11 | May 27 | Apr 30 | Oct 1 | 142 | Plan sowing from this date → |
| SIDNEY | May 11 | May 25 | Apr 30 | Sep 27 | 137 | Plan sowing from this date → |
| BAKER | May 12 | May 27 | Apr 29 | Sep 26 | 135 | Plan sowing from this date → |
| CRESTON | May 12 | May 26 | Apr 30 | Sep 25 | 134 | Plan sowing from this date → |
| GREAT FALLS WFO | May 12 | May 27 | Apr 30 | Sep 28 | 138 | Plan sowing from this date → |
| HUNTLEY EXP STN | May 12 | May 26 | Apr 30 | Sep 25 | 136 | Plan sowing from this date → |
| NASHUA #2 | May 12 | May 26 | Apr 30 | Sep 24 | 134 | Plan sowing from this date → |
| SAINT IGNATIUS | May 12 | Jun 1 | Apr 28 | Oct 2 | 142 | Plan sowing from this date → |
| SAND CREEK | May 12 | May 27 | Apr 30 | Sep 27 | 136 | Plan sowing from this date → |
| SAVAGE | May 12 | May 26 | May 1 | Sep 25 | 135 | Plan sowing from this date → |
| TERRY | May 12 | May 25 | Apr 30 | Sep 28 | 137 | Plan sowing from this date → |
| BRADY 27 ENE (THE KNEES) | May 13 | May 29 | Apr 30 | Sep 29 | 137 | Plan sowing from this date → |
| FAIRFIELD | May 13 | Jun 1 | Apr 28 | Sep 27 | 135 | Plan sowing from this date → |
| HARDIN | May 13 | May 26 | Apr 30 | Sep 29 | 135 | Plan sowing from this date → |
| POWDERVILLE 8 NNE | May 13 | May 31 | May 1 | Sep 25 | 132 | Plan sowing from this date → |
| ST MARIE | May 13 | May 26 | May 2 | Sep 27 | 134 | Plan sowing from this date → |
| WOLF POINT 34 NE | May 13 | May 25 | Apr 30 | Sep 28 | 137 | Plan sowing from this date → |
| BIDDLE 8 SW | May 14 | May 27 | May 2 | Sep 28 | 134 | Plan sowing from this date → |
| BIG TIMBER | May 14 | May 27 | May 2 | Sep 26 | 133 | Plan sowing from this date → |
| BRIDGER 2 N | May 14 | May 30 | May 2 | Sep 24 | 129 | Plan sowing from this date → |
| CHINOOK | May 14 | May 27 | May 1 | Sep 23 | 130 | Plan sowing from this date → |
| GERALDINE | May 14 | May 28 | May 2 | Sep 26 | 134 | Plan sowing from this date → |
| LEWISTOWN | May 14 | May 27 | May 2 | Sep 28 | 135 | Plan sowing from this date → |
| ROY 8 NE | May 14 | May 29 | May 3 | Sep 24 | 134 | Plan sowing from this date → |
| TROY | May 14 | May 31 | Apr 29 | Sep 25 | 132 | Plan sowing from this date → |
| COLSTRIP | May 15 | May 28 | May 2 | Sep 30 | 138 | Plan sowing from this date → |
| FT ASSINIBOINE | May 15 | May 28 | May 4 | Sep 24 | 130 | Plan sowing from this date → |
| FT BENTON | May 15 | May 30 | May 3 | Sep 22 | 129 | Plan sowing from this date → |
| HAVRE CITY CO AP | May 15 | May 27 | May 3 | Sep 23 | 129 | Plan sowing from this date → |
| HINSDALE 4 SW | May 15 | May 30 | May 3 | Sep 26 | 132 | Plan sowing from this date → |
| ROCK SPRINGS | May 15 | May 27 | May 2 | Sep 25 | 132 | Plan sowing from this date → |
| SACO 1 NNW | May 15 | May 26 | May 3 | Sep 23 | 130 | Plan sowing from this date → |
| SKQ DAM | May 15 | Jun 1 | May 3 | Sep 28 | 134 | Plan sowing from this date → |
| SWEETGRASS | May 15 | May 28 | May 3 | Sep 25 | 132 | Plan sowing from this date → |
| BAKER MUNI AP | May 16 | May 29 | May 4 | Sep 26 | 132 | Plan sowing from this date → |
| BROADUS | May 16 | May 29 | May 2 | Sep 28 | 135 | Plan sowing from this date → |
| BYNUM 4 SSE | May 16 | May 28 | May 2 | Sep 27 | 133 | Plan sowing from this date → |
| FLATWILLOW 4 ENE | May 16 | May 31 | May 3 | Sep 28 | 132 | Plan sowing from this date → |
| FORTINE 1 N | May 16 | Jun 3 | May 3 | Sep 18 | 121 | Plan sowing from this date → |
| FT BELKNAP 2 SW | May 16 | May 28 | May 6 | Sep 22 | 128 | Plan sowing from this date → |
| HARLEM | May 16 | May 31 | May 4 | Sep 21 | 125 | Plan sowing from this date → |
| MALTA 35 S | May 16 | May 29 | May 4 | Sep 23 | 128 | Plan sowing from this date → |
| MEDICINE LAKE 3 SE | May 16 | May 30 | May 4 | Sep 18 | 125 | Plan sowing from this date → |
| MISSOULA INTL AP | May 16 | Jun 1 | May 3 | Sep 26 | 130 | Plan sowing from this date → |
| TIBER DAM | May 16 | May 30 | May 2 | Sep 23 | 129 | Plan sowing from this date → |
| VIDA 6 NE | May 16 | May 31 | May 2 | Sep 22 | 129 | Plan sowing from this date → |
| WHITEFISH | May 16 | Jun 6 | May 2 | Sep 25 | 129 | Plan sowing from this date → |
| WINIFRED | May 16 | May 30 | May 5 | Sep 23 | 127 | Plan sowing from this date → |
| WOLF POINT INTL AP | May 16 | May 29 | May 5 | Sep 20 | 125 | Plan sowing from this date → |
| BIG SANDY | May 17 | Jun 4 | May 4 | Sep 25 | 128 | Plan sowing from this date → |
| CIRCLE | May 17 | May 31 | May 4 | Sep 22 | 126 | Plan sowing from this date → |
| MOORHEAD 9 NE | May 17 | May 31 | May 5 | Sep 22 | 126 | Plan sowing from this date → |
| RIDGEWAY 1 S | May 17 | Jun 1 | May 5 | Sep 22 | 127 | Plan sowing from this date → |
| RYEGATE | May 17 | May 30 | May 3 | Sep 23 | 127 | Plan sowing from this date → |
| SUNBURST 8 E | May 17 | May 31 | May 2 | Sep 25 | 129 | Plan sowing from this date → |
| SUPERIOR | May 17 | Jun 8 | May 1 | Sep 23 | 125 | Plan sowing from this date → |
| SWAN LAKE | May 17 | Jun 4 | May 4 | Sep 19 | 121 | Plan sowing from this date → |
| VALIER | May 17 | May 31 | May 3 | Sep 24 | 129 | Plan sowing from this date → |
| ALBERTON | May 18 | Jun 6 | May 5 | Sep 25 | 126 | Plan sowing from this date → |
| BRANDENBERG | May 18 | May 30 | May 6 | Sep 22 | 126 | Plan sowing from this date → |
| CARLYLE 13 NW | May 18 | May 31 | May 4 | Sep 29 | 134 | Plan sowing from this date → |
| JORDAN AP | May 18 | May 31 | May 6 | Sep 20 | 123 | Plan sowing from this date → |
| VALENTINE | May 18 | May 31 | May 7 | Sep 21 | 124 | Plan sowing from this date → |
| W GLACIER | May 18 | Jun 4 | May 6 | Sep 20 | 124 | Plan sowing from this date → |
| WESTBY | May 18 | May 30 | May 6 | Sep 21 | 125 | Plan sowing from this date → |
| ZORTMAN | May 18 | Jun 1 | May 4 | Sep 23 | 126 | Plan sowing from this date → |
| AUGUSTA | May 19 | May 31 | May 4 | Sep 21 | 125 | Plan sowing from this date → |
| GREAT FALLS INTL AP | May 19 | Jun 2 | May 7 | Sep 24 | 126 | Plan sowing from this date → |
| HOLTER DAM | May 19 | Jun 8 | May 6 | Sep 24 | 124 | Plan sowing from this date → |
| LEWISTOWN 11ESE | May 19 | Jun 1 | May 7 | Sep 25 | 128 | Plan sowing from this date → |
| LIVINGSTON 12 S | May 19 | Jun 11 | May 5 | Sep 25 | 125 | Plan sowing from this date → |
| PORT OF MORGAN | May 19 | Jun 2 | May 5 | Sep 22 | 124 | Plan sowing from this date → |
| RAYMOND BORDER STN | May 19 | Jun 1 | May 6 | Sep 23 | 125 | Plan sowing from this date → |
| TOWNSEND 3SE | May 19 | Jun 2 | May 8 | Sep 19 | 122 | Plan sowing from this date → |
| TURNER 11N | May 19 | Jun 1 | May 7 | Sep 21 | 124 | Plan sowing from this date → |
| BREDETTE | May 20 | Jun 1 | May 8 | Sep 21 | 122 | Plan sowing from this date → |
| BROCKWAY 3 WSW | May 20 | Jun 5 | May 6 | Sep 19 | 121 | Plan sowing from this date → |
| CHOTEAU 8NE | May 20 | Jun 4 | May 7 | Sep 22 | 123 | Plan sowing from this date → |
| CONRAD | May 20 | Jun 3 | May 9 | Sep 19 | 119 | Plan sowing from this date → |
| EKALAKA | May 20 | Jun 1 | May 7 | Sep 23 | 126 | Plan sowing from this date → |
| GRASS RANGE | May 20 | Jun 6 | May 6 | Sep 24 | 126 | Plan sowing from this date → |
| HERON 2 NW | May 20 | Jun 5 | May 4 | Sep 20 | 119 | Plan sowing from this date → |
| LINDBERGH LAKE | May 20 | Jun 7 | May 7 | Sep 22 | 120 | Plan sowing from this date → |
| LOMA | May 20 | Jun 3 | May 8 | Sep 19 | 120 | Plan sowing from this date → |
| MILDRED 5 N | May 20 | Jun 2 | May 6 | Sep 22 | 124 | Plan sowing from this date → |
| ROUNDUP | May 20 | Jun 2 | May 6 | Sep 21 | 124 | Plan sowing from this date → |
| TROUT CREEK RS | May 20 | Jun 9 | May 5 | Sep 21 | 122 | Plan sowing from this date → |
| CASCADE 5 S | May 21 | Jun 6 | May 5 | Sep 19 | 120 | Plan sowing from this date → |
| CULBERTSON | May 21 | Jun 3 | May 8 | Sep 20 | 120 | Plan sowing from this date → |
| GARDINER | May 21 | Jun 9 | May 5 | Sep 27 | 128 | Plan sowing from this date → |
| HAMILTON | May 21 | Jun 6 | May 7 | Sep 22 | 122 | Plan sowing from this date → |
| INGOMAR 9 E | May 21 | Jun 4 | May 8 | Sep 19 | 120 | Plan sowing from this date → |
| JOPLIN | May 21 | Jun 6 | May 8 | Sep 19 | 119 | Plan sowing from this date → |
| JORDAN | May 21 | Jun 2 | May 8 | Sep 18 | 118 | Plan sowing from this date → |
| PLEVNA | May 21 | Jun 4 | May 9 | Sep 20 | 121 | Plan sowing from this date → |
| ROGERS PASS 9 NNE | May 21 | Jun 8 | May 7 | Sep 15 | 115 | Plan sowing from this date → |
| WYOLA 1 SW | May 21 | Jun 2 | May 9 | Sep 17 | 117 | Plan sowing from this date → |
| MIZPAH 4 NNW | May 22 | Jun 7 | May 9 | Sep 15 | 117 | Plan sowing from this date → |
| POMPEYS PILLAR 15N | May 22 | Jun 7 | May 9 | Sep 22 | 121 | Plan sowing from this date → |
| RAYNESFORD 2 NNW | May 22 | Jun 9 | May 7 | Sep 23 | 123 | Plan sowing from this date → |
| ROUNDUP 15 SW | May 22 | Jun 4 | May 11 | Sep 15 | 114 | Plan sowing from this date → |
| STEVENSVILLE | May 22 | Jun 13 | May 7 | Sep 19 | 115 | Plan sowing from this date → |
| BOZEMAN 6 W EXP FARM | May 23 | Jun 12 | May 5 | Sep 23 | 123 | Plan sowing from this date → |
| BUSBY | May 23 | Jun 7 | May 12 | Sep 15 | 113 | Plan sowing from this date → |
| CARTER 14 W | May 23 | Jun 9 | May 10 | Sep 23 | 120 | Plan sowing from this date → |
| CHINOOK 35SE | May 23 | Jun 3 | May 11 | Sep 23 | 121 | Plan sowing from this date → |
| DUNKIRK 19NNE | May 23 | Jun 8 | May 12 | Sep 14 | 112 | Plan sowing from this date → |
| HARLOWTON | May 23 | Jun 6 | May 12 | Sep 16 | 113 | Plan sowing from this date → |
| LEWISTOWN MUNI AP | May 23 | Jun 8 | May 11 | Sep 21 | 119 | Plan sowing from this date → |
| LIBBY 1 NE RS | May 23 | Jun 7 | May 9 | Sep 21 | 120 | Plan sowing from this date → |
| RUDYARD 19S | May 23 | Jun 3 | May 12 | Sep 19 | 119 | Plan sowing from this date → |
| SHELBY | May 23 | Jun 6 | May 11 | Sep 16 | 115 | Plan sowing from this date → |
| WESTERN AG RSCH CTR | May 23 | Jun 10 | May 8 | Sep 21 | 118 | Plan sowing from this date → |
| CHESTER | May 24 | Jun 9 | May 11 | Sep 17 | 115 | Plan sowing from this date → |
| CUT BANK MUNI AP | May 24 | Jun 5 | May 11 | Sep 15 | 113 | Plan sowing from this date → |
| DARBY | May 24 | Jun 14 | May 6 | Sep 23 | 118 | Plan sowing from this date → |
| GILDFORD | May 24 | Jun 7 | May 12 | Sep 15 | 114 | Plan sowing from this date → |
| HARLEM 20S | May 24 | Jun 11 | May 12 | Sep 22 | 118 | Plan sowing from this date → |
| LAURIN 2NE | May 24 | Jun 13 | May 11 | Sep 22 | 117 | Plan sowing from this date → |
| RAPELJE | May 24 | Jun 11 | May 11 | Sep 21 | 116 | Plan sowing from this date → |
| SHONKIN 7 S | May 24 | Jun 10 | May 6 | Sep 21 | 119 | Plan sowing from this date → |
| WOLF POINT 29 ENE | May 24 | Jun 6 | May 12 | Sep 14 | 110 | Plan sowing from this date → |
| COHAGEN | May 25 | Jun 9 | May 12 | Sep 14 | 110 | Plan sowing from this date → |
| CONTENT 4 NNE | May 25 | Jun 8 | May 11 | Sep 14 | 110 | Plan sowing from this date → |
| PLENTYWOOD | May 25 | Jun 8 | May 13 | Sep 14 | 111 | Plan sowing from this date → |
| SONNETTE 7 SW | May 25 | Jun 7 | May 12 | Sep 19 | 115 | Plan sowing from this date → |
| STANFORD | May 25 | Jun 15 | May 10 | Sep 21 | 118 | Plan sowing from this date → |
| BOZEMAN GALLATIN FLD | May 26 | Jun 12 | May 11 | Sep 16 | 112 | Plan sowing from this date → |
| BOZEMAN MONTANA STATE UNIV | May 26 | Jun 14 | May 9 | Sep 22 | 116 | Plan sowing from this date → |
| HYSHAM 25 SSE | May 26 | Jun 13 | May 12 | Sep 16 | 111 | Plan sowing from this date → |
| LOGAN LANDFILL | May 26 | Jun 12 | May 11 | Sep 15 | 111 | Plan sowing from this date → |
| RYEGATE 18 NNW | May 26 | Jun 13 | May 12 | Sep 18 | 112 | Plan sowing from this date → |
| SIMPSON 6 N - WILDHORSE | May 26 | Jun 8 | May 12 | Sep 15 | 110 | Plan sowing from this date → |
| TERRY 21 NNW | May 26 | Jun 13 | May 13 | Sep 17 | 113 | Plan sowing from this date → |
| COLUMBUS | May 27 | Jun 12 | May 14 | Sep 14 | 108 | Plan sowing from this date → |
| GIBSON 2 NE | May 27 | Jun 12 | May 12 | Sep 18 | 113 | Plan sowing from this date → |
| LIVINGSTON MISSION FLD | May 27 | Jun 14 | May 13 | Sep 14 | 108 | Plan sowing from this date → |
| WIBAUX 2 E | May 27 | Jun 13 | May 15 | Sep 16 | 112 | Plan sowing from this date → |
| CHOTEAU | May 28 | Jun 20 | May 15 | Sep 12 | 104 | Plan sowing from this date → |
| DEL BONITA | May 28 | Jun 12 | May 12 | Sep 16 | 110 | Plan sowing from this date → |
| MOCCASIN EXP STN | May 28 | Jun 19 | May 13 | Sep 20 | 112 | Plan sowing from this date → |
| REDSTONE | May 28 | Jun 13 | May 15 | Sep 7 | 101 | Plan sowing from this date → |
| SCOBEY 4 NW | May 28 | Jun 13 | May 16 | Sep 6 | 99 | Plan sowing from this date → |
| JOLIET | May 29 | Jun 17 | May 14 | Sep 15 | 107 | Plan sowing from this date → |
| HARLOWTON 11NW | May 30 | Jun 17 | May 16 | Sep 20 | 110 | Plan sowing from this date → |
| RUDYARD 21 N | May 30 | Jun 15 | May 17 | Sep 11 | 103 | Plan sowing from this date → |
| KALISPELL GLACIER AP | May 31 | Jun 22 | May 13 | Sep 10 | 100 | Plan sowing from this date → |
| LEWISTOWN 11 SSE | May 31 | Jun 18 | May 16 | Sep 14 | 105 | Plan sowing from this date → |
| ANACONDA | Jun 1 | Jun 25 | May 14 | Sep 14 | 105 | Plan sowing from this date → |
| DENTON | Jun 1 | Jun 26 | May 15 | Sep 11 | 101 | Plan sowing from this date → |
| JUDITH GAP | Jun 1 | Jun 16 | May 17 | Sep 15 | 104 | Plan sowing from this date → |
| NYE #2 | Jun 1 | Jun 21 | May 15 | Sep 11 | 100 | Plan sowing from this date → |
| OPHEIM 10 N | Jun 1 | Jun 18 | May 20 | Sep 7 | 99 | Plan sowing from this date → |
| ALBION 1 N | Jun 2 | Jun 21 | May 18 | Sep 6 | 95 | Plan sowing from this date → |
| DILLON AP | Jun 2 | Jun 21 | May 17 | Sep 13 | 101 | Plan sowing from this date → |
| SUN RVR 4 S | Jun 2 | Jun 21 | May 18 | Sep 10 | 96 | Plan sowing from this date → |
| JUDITH GAP 13 E | Jun 3 | Jun 25 | May 19 | Sep 15 | 100 | Plan sowing from this date → |
| MARTINSDALE 3 NNW | Jun 3 | Jun 25 | May 20 | Sep 8 | 94 | Plan sowing from this date → |
| RED LODGE | Jun 3 | Jun 18 | May 19 | Sep 19 | 106 | Plan sowing from this date → |
| ST. MARY 1 SSW | Jun 3 | Jun 23 | May 19 | Sep 8 | 94 | Plan sowing from this date → |
| ADEL | Jun 4 | Jun 22 | May 22 | Sep 12 | 98 | Plan sowing from this date → |
| AUSTIN 1 W | Jun 4 | Jun 18 | May 18 | Sep 14 | 100 | Plan sowing from this date → |
| VIRGINIA CITY | Jun 4 | Jun 23 | May 17 | Sep 18 | 106 | Plan sowing from this date → |
| WHITE SULPHUR SPRINGS #2 | Jun 4 | Jun 20 | May 21 | Sep 11 | 97 | Plan sowing from this date → |
| WILSALL 1S | Jun 4 | Jun 23 | May 19 | Sep 6 | 92 | Plan sowing from this date → |
| DILLON U OF MONTANA WESTERN | Jun 5 | Jun 23 | May 18 | Sep 13 | 98 | Plan sowing from this date → |
| MYSTIC LAKE | Jun 5 | Jun 21 | May 22 | Sep 14 | 99 | Plan sowing from this date → |
| OPHEIM 12 SSE | Jun 5 | Jun 23 | May 22 | Sep 2 | 89 | Plan sowing from this date → |
| ALDER 17 S | Jun 6 | Jun 25 | May 20 | Sep 14 | 98 | Plan sowing from this date → |
| NEIHART 8 NNW | Jun 6 | Jun 28 | May 23 | Sep 12 | 99 | Plan sowing from this date → |
| BOULDER | Jun 7 | Jun 25 | May 24 | Sep 8 | 90 | Plan sowing from this date → |
| E GLACIER | Jun 8 | Jul 1 | May 24 | Sep 5 | 88 | Plan sowing from this date → |
| TWIN BRIDGES | Jun 8 | Jul 1 | May 22 | Sep 2 | 82 | Plan sowing from this date → |
| WILSALL 8 ENE | Jun 8 | Jun 30 | May 23 | Sep 7 | 89 | Plan sowing from this date → |
| BLACKLEAF | Jun 9 | Jul 2 | May 25 | Sep 3 | 86 | Plan sowing from this date → |
| ELLISTON | Jun 9 | Jun 26 | May 23 | Sep 8 | 91 | Plan sowing from this date → |
| MELVILLE 4 W | Jun 9 | Jun 27 | May 26 | Sep 7 | 88 | Plan sowing from this date → |
| DIVIDE | Jun 10 | Jul 2 | May 23 | Sep 7 | 85 | Plan sowing from this date → |
| LIMA | Jun 11 | Jun 30 | May 24 | Sep 10 | 89 | Plan sowing from this date → |
| MILLEGAN 14 SE | Jun 11 | Jul 3 | May 27 | Sep 6 | 86 | Plan sowing from this date → |
| GIBSON DAM | Jun 12 | Jul 5 | May 25 | Sep 8 | 88 | Plan sowing from this date → |
| ST MARY | Jun 12 | Jul 3 | May 27 | Sep 5 | 82 | Plan sowing from this date → |
| BUTTE BERT MOONEY AP | Jun 13 | Jul 1 | May 27 | Sep 5 | 83 | Plan sowing from this date → |
| HEBGEN DAM | Jun 15 | Jul 7 | May 29 | Sep 10 | 87 | Plan sowing from this date → |
| LEWISTOWN 42 WSW | Jun 15 | Jul 8 | May 31 | Sep 4 | 77 | Plan sowing from this date → |
| ENNIS | Jun 16 | Jul 6 | May 30 | Sep 4 | 78 | Plan sowing from this date → |
| TIZER GARDENS | Jun 18 | Jul 3 | May 30 | Sep 5 | 81 | Plan sowing from this date → |
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 transplant tomatoes and peppers, both killed by a single frost. 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.