Wisconsin frost dates
Across 204 NOAA climate stations in Wisconsin, the median last spring frost (32°F) ranges from Apr 19 at Kenosha to Jun 3 at North Pelican; the typical station sees its last frost around May 5 and its first fall frost around Oct 6.
“Median” dates have a 50% chance of a later spring frost or an earlier fall frost. “10% risk” dates are the safer choice for tender plants: only 1 year in 10 has frost beyond them. Source: NOAA NCEI 1991–2020 Climate Normals. Elevation matters: within a state, frost dates can differ by a month or more between valleys and hills.
| Station | Elevation | Last frost (median) | Last frost (10% risk) | First frost (median) | First frost (10% risk) | Growing season |
|---|---|---|---|---|---|---|
| Afton - Janesville Wwtp | 762 ft | Apr 26 | May 11 | Oct 15 | Oct 1 | 170 days |
| Alma Dam 4 | 670 ft | Apr 28 | May 9 | Oct 14 | Sep 29 | 168 days |
| Amery | 1,070 ft | May 5 | May 21 | Oct 4 | Sep 21 | 151 days |
| Antigo | 1,519 ft | May 14 | May 28 | Sep 30 | Sep 14 | 139 days |
| Appleton | 792 ft | May 4 | May 20 | Oct 6 | Sep 23 | 154 days |
| Arlington | 1,052 ft | May 4 | May 18 | Oct 6 | Sep 23 | 154 days |
| Ashland 3S | 826 ft | May 20 | Jun 3 | Oct 2 | Sep 19 | 133 days |
| Ashland Kennedy Mem AP | 826 ft | May 23 | Jun 6 | Sep 29 | Sep 14 | 125 days |
| Augusta Rs | 960 ft | May 7 | May 20 | Oct 1 | Sep 17 | 146 days |
| Baldwin | 1,100 ft | May 6 | May 21 | Oct 2 | Sep 18 | 148 days |
| Baraboo | 823 ft | May 5 | May 21 | Oct 5 | Sep 22 | 152 days |
| Bayfield 6 N | 820 ft | May 20 | Jun 5 | Oct 8 | Sep 21 | 141 days |
| Bayfield Fish Hatchery | 615 ft | May 23 | Jun 5 | Oct 2 | Sep 17 | 131 days |
| Beaver Dam Wwtp | 861 ft | May 2 | May 16 | Oct 9 | Sep 25 | 157 days |
| Belgium Wwtp | 731 ft | May 5 | May 22 | Oct 12 | Sep 27 | 159 days |
| Beloit | 788 ft | May 1 | May 16 | Oct 12 | Sep 28 | 162 days |
| Berlin Wwtp | 766 ft | May 1 | May 16 | Oct 8 | Sep 24 | 158 days |
| Big Falls Hydro | 1,205 ft | May 7 | May 22 | Oct 3 | Sep 18 | 147 days |
| Blair | 855 ft | May 9 | May 23 | Oct 1 | Sep 18 | 143 days |
| Bloomer | 990 ft | May 5 | May 19 | Oct 3 | Sep 20 | 151 days |
| Boscobel AP | 672 ft | May 3 | May 18 | Oct 7 | Sep 25 | 155 days |
| Brillion | 810 ft | May 6 | May 21 | Oct 6 | Sep 23 | 151 days |
| Brodhead Wwtp | 780 ft | Apr 29 | May 14 | Oct 12 | Sep 28 | 165 days |
| Brookfield Wwtp | 830 ft | Apr 30 | May 15 | Oct 14 | Sep 28 | 164 days |
| Brule Rs | 1,000 ft | May 24 | Jun 6 | Sep 26 | Sep 9 | 124 days |
| Burlington | 751 ft | May 5 | May 23 | Oct 9 | Sep 24 | 156 days |
| Butternut 3SW | 1,570 ft | May 22 | Jun 4 | Sep 24 | Sep 10 | 126 days |
| Cashton | 1,370 ft | Apr 27 | May 11 | Oct 14 | Oct 1 | 170 days |
| Cashton 3NNW | 939 ft | May 6 | May 20 | Oct 3 | Sep 20 | 150 days |
| Charmany Farm | 1,046 ft | Apr 28 | May 11 | Oct 15 | Sep 29 | 169 days |
| Chilton | 840 ft | May 1 | May 17 | Oct 14 | Sep 29 | 162 days |
| Clam Lake 4W | 1,498 ft | May 16 | May 27 | Sep 30 | Sep 17 | 136 days |
| Clinton Wwtp | 924 ft | Apr 30 | May 17 | Oct 10 | Sep 26 | 161 days |
| Clintonville | 802 ft | May 4 | May 19 | Oct 6 | Sep 21 | 154 days |
| Crivitz High Falls | 950 ft | May 26 | Jun 11 | Sep 22 | Sep 6 | 118 days |
| Cumberland | 1,240 ft | May 5 | May 18 | Oct 4 | Sep 23 | 152 days |
| Dalton | 860 ft | May 6 | May 22 | Oct 2 | Sep 20 | 150 days |
| Danbury | 950 ft | May 11 | May 28 | Sep 30 | Sep 15 | 138 days |
| Darlington Wwtp | 854 ft | May 3 | May 19 | Oct 4 | Sep 20 | 153 days |
| Delavan Wwtp | 882 ft | Apr 28 | May 14 | Oct 14 | Sep 28 | 168 days |
| Denmark Wwtp | 811 ft | May 6 | May 20 | Oct 12 | Sep 30 | 158 days |
| Dodge | 685 ft | May 5 | May 19 | Oct 5 | Sep 21 | 152 days |
| Dodgeville Wwtp | 1,118 ft | May 3 | May 17 | Oct 7 | Sep 25 | 157 days |
| Drummond | 1,340 ft | May 20 | Jun 2 | Oct 1 | Sep 19 | 132 days |
| Durand | 705 ft | May 1 | May 15 | Oct 10 | Sep 26 | 162 days |
| Eagle Rvr | 1,623 ft | May 25 | Jun 6 | Sep 24 | Sep 8 | 121 days |
| Eau Claire 3SW | 880 ft | Apr 24 | May 7 | Oct 14 | Sep 26 | 170 days |
| Eau Claire Rgnl AP | 885 ft | May 8 | May 21 | Oct 4 | Sep 20 | 149 days |
| Ellsworth 1E | 1,030 ft | May 13 | May 27 | Sep 29 | Sep 15 | 139 days |
| Ephraim 1NE-Wwtp | 733 ft | May 14 | May 28 | Oct 18 | Oct 1 | 155 days |
| Florence | 1,300 ft | May 24 | Jun 8 | Sep 25 | Sep 7 | 121 days |
| Fond Du Lac 2 Sw | 772 ft | Apr 27 | May 11 | Oct 19 | Oct 2 | 174 days |
| Fond Du Lac Co AP | 809 ft | May 1 | May 17 | Oct 10 | Sep 27 | 160 days |
| Fond Du Lac Wwtp | 750 ft | May 1 | May 17 | Oct 12 | Sep 28 | 162 days |
| Forestville-4E | 690 ft | May 6 | May 20 | Oct 17 | Oct 1 | 163 days |
| Foxboro | 932 ft | Jun 1 | Jun 14 | Sep 22 | Sep 8 | 113 days |
| Friendship | 945 ft | May 9 | May 23 | Oct 3 | Sep 19 | 147 days |
| Ft Atkinson | 800 ft | Apr 28 | May 17 | Oct 13 | Sep 29 | 166 days |
| Gays Mills | 689 ft | May 3 | May 18 | Oct 7 | Sep 25 | 156 days |
| Genoa Dam 8 | 639 ft | Apr 22 | May 5 | Oct 17 | Oct 4 | 178 days |
| Germantown | 850 ft | May 6 | May 25 | Oct 8 | Sep 26 | 154 days |
| Goodman Sanitary Dist | 1,448 ft | May 24 | Jun 7 | Sep 30 | Sep 16 | 128 days |
| Gordon | 1,040 ft | May 22 | Jun 4 | Sep 26 | Sep 11 | 126 days |
| Grafton Wwtp | 741 ft | Apr 23 | May 9 | Oct 24 | Oct 8 | 182 days |
| Grantsburg | 990 ft | May 11 | May 28 | Oct 1 | Sep 16 | 141 days |
| Green Bay | 682 ft | Apr 30 | May 16 | Oct 9 | Sep 24 | 161 days |
| Green Bay Botanical | 694 ft | May 7 | May 22 | Oct 9 | Sep 23 | 154 days |
| Green Bay Wfo | 682 ft | May 1 | May 16 | Oct 11 | Sep 26 | 160 days |
| Hales Corners/Whitnall Park/Bo | 774 ft | May 3 | May 19 | Oct 14 | Sep 30 | 162 days |
| Hancock Exp Farm | 1,092 ft | May 10 | May 24 | Oct 3 | Sep 20 | 146 days |
| Hartford Wwtp | 961 ft | May 8 | May 24 | Oct 3 | Sep 20 | 148 days |
| Hayward Muni AP | 1,204 ft | May 23 | Jun 6 | Sep 22 | Sep 5 | 122 days |
| Hayward Rs | 1,200 ft | May 22 | Jun 6 | Sep 23 | Sep 3 | 124 days |
| Hillsboro | 940 ft | May 5 | May 18 | Oct 4 | Sep 23 | 153 days |
| Hillsboro 2SW | 1,043 ft | May 12 | May 26 | Sep 29 | Sep 17 | 138 days |
| Hingham Wwtp | 763 ft | May 3 | May 18 | Oct 16 | Oct 2 | 165 days |
| Holcombe | 1,057 ft | May 5 | May 21 | Oct 2 | Sep 19 | 149 days |
| Horicon Wwtp | 881 ft | May 1 | May 19 | Oct 10 | Sep 27 | 158 days |
| Hurley | 1,444 ft | May 24 | Jun 7 | Sep 28 | Sep 13 | 128 days |
| Hustisford Wwtp | 864 ft | Apr 28 | May 13 | Oct 10 | Sep 26 | 164 days |
| Jackson | 903 ft | Apr 30 | May 15 | Oct 15 | Oct 1 | 167 days |
| Jefferson Wwtp | 783 ft | Apr 25 | May 9 | Oct 18 | Oct 2 | 173 days |
| Jim Falls 3NW | 1,070 ft | May 1 | May 16 | Oct 8 | Sep 22 | 158 days |
| Jump Rvr 3E | 1,265 ft | May 20 | Jun 4 | Sep 23 | Sep 6 | 125 days |
| Kenosha | 600 ft | Apr 19 | May 3 | Oct 26 | Oct 11 | 189 days |
| Kenosha Rgnl AP | 743 ft | Apr 28 | May 13 | Oct 19 | Oct 1 | 174 days |
| Kewaunee | 593 ft | May 1 | May 17 | Oct 18 | Oct 2 | 168 days |
| La Crosse Muni AP | 652 ft | Apr 23 | May 6 | Oct 17 | Oct 3 | 177 days |
| La Crosse Wfo | 1,307 ft | Apr 27 | May 12 | Oct 13 | Sep 28 | 167 days |
| Ladysmith 3W | 1,130 ft | May 27 | Jun 8 | Sep 22 | Sep 6 | 117 days |
| Lake Geneva Wwtp | 846 ft | Apr 25 | May 10 | Oct 21 | Oct 5 | 179 days |
| Lake Mills Wwtp | 811 ft | Apr 29 | May 13 | Oct 14 | Sep 29 | 167 days |
| Lakewood 3 Ne | 1,196 ft | May 22 | Jun 3 | Sep 28 | Sep 12 | 129 days |
| Lancaster 4 Wsw | 1,040 ft | Apr 27 | May 11 | Oct 11 | Sep 27 | 166 days |
| Laona 6 Sw | 1,695 ft | May 19 | Jun 2 | Sep 29 | Sep 15 | 131 days |
| Lodi | 824 ft | May 1 | May 15 | Oct 10 | Sep 27 | 162 days |
| Lone Rock Tri Co AP | 717 ft | Apr 30 | May 14 | Oct 9 | Sep 25 | 161 days |
| Luck | 1,220 ft | May 6 | May 20 | Oct 4 | Sep 19 | 149 days |
| Lynxville Dam 9 | 633 ft | Apr 24 | May 8 | Oct 17 | Oct 4 | 175 days |
| Madeline Island | 660 ft | May 20 | Jun 3 | Oct 9 | Sep 25 | 140 days |
| Madison Dane Rgnl AP | 866 ft | May 1 | May 16 | Oct 10 | Sep 26 | 160 days |
| Manitowoc | 584 ft | Apr 30 | May 15 | Oct 20 | Oct 3 | 171 days |
| Marinette | 589 ft | May 4 | May 20 | Oct 11 | Sep 29 | 160 days |
| Markesan | 861 ft | May 8 | May 23 | Oct 2 | Sep 19 | 144 days |
| Marshfield Exp Farm | 1,237 ft | May 5 | May 20 | Oct 5 | Sep 22 | 150 days |
| Marshfield Muni AP | 1,255 ft | May 5 | May 20 | Oct 5 | Sep 21 | 152 days |
| Mather 3 Nw | 978 ft | May 6 | May 20 | Oct 3 | Sep 19 | 148 days |
| Mauston 1 Se | 865 ft | May 2 | May 15 | Oct 7 | Sep 26 | 158 days |
| Mazomanie Wwtp | 764 ft | May 7 | May 22 | Oct 1 | Sep 18 | 148 days |
| Medford | 1,470 ft | May 11 | May 26 | Oct 1 | Sep 17 | 141 days |
| Mellen 4 Ne | 1,300 ft | May 26 | Jun 9 | Sep 27 | Sep 12 | 125 days |
| Menomonie | 780 ft | May 9 | May 24 | Oct 1 | Sep 19 | 143 days |
| Merrill | 1,250 ft | May 11 | May 27 | Sep 30 | Sep 17 | 139 days |
| Milwaukee Mitchell AP | 670 ft | Apr 19 | May 2 | Oct 29 | Oct 15 | 192 days |
| Minocqua | 1,601 ft | May 23 | Jun 6 | Sep 27 | Sep 9 | 127 days |
| Minong 5 Wsw | 1,075 ft | May 10 | May 26 | Oct 4 | Sep 21 | 144 days |
| Mondovi | 830 ft | May 10 | May 25 | Oct 2 | Sep 19 | 144 days |
| Monroe Wwtp | 991 ft | Apr 27 | May 12 | Oct 14 | Sep 29 | 170 days |
| Montello | 786 ft | May 3 | May 18 | Oct 5 | Sep 22 | 153 days |
| Mt Mary College | 715 ft | Apr 26 | May 12 | Oct 18 | Oct 2 | 173 days |
| Necedah | 922 ft | May 17 | Jun 1 | Sep 25 | Sep 12 | 131 days |
| Necedah 5 Wnw | 933 ft | May 1 | May 14 | Oct 3 | Sep 20 | 157 days |
| Neillsville 3ESE | 1,080 ft | May 10 | May 25 | Oct 1 | Sep 18 | 144 days |
| New London | 800 ft | May 4 | May 19 | Oct 6 | Sep 22 | 153 days |
| North Pelican | 1,610 ft | Jun 3 | Jun 27 | Sep 18 | Sep 1 | 106 days |
| Oconomowoc Wwtp | 858 ft | Apr 30 | May 17 | Oct 12 | Sep 29 | 164 days |
| Oconto 4 W | 660 ft | May 9 | May 23 | Oct 6 | Sep 22 | 150 days |
| Oshkosh | 750 ft | Apr 24 | May 8 | Oct 20 | Oct 4 | 178 days |
| Oshkosh Wittman AP | 782 ft | Apr 30 | May 13 | Oct 13 | Sep 29 | 165 days |
| Owen 1E | 1,238 ft | May 13 | May 29 | Sep 26 | Sep 12 | 136 days |
| Paddock Lake | 775 ft | Apr 30 | May 16 | Oct 15 | Sep 30 | 167 days |
| Park Falls Dnr Hq | 1,525 ft | May 15 | May 30 | Sep 28 | Sep 16 | 134 days |
| Pattison Ranger Staion | 1,100 ft | May 18 | Jun 3 | Oct 3 | Sep 20 | 135 days |
| Pell Lake | 840 ft | Apr 30 | May 16 | Oct 13 | Sep 28 | 164 days |
| Peshtigo | 600 ft | May 11 | May 26 | Oct 5 | Sep 21 | 145 days |
| Platteville | 990 ft | Apr 30 | May 13 | Oct 13 | Sep 29 | 166 days |
| Plymouth Wwtp | 828 ft | May 3 | May 20 | Oct 10 | Sep 28 | 159 days |
| Port Washington | 594 ft | Apr 27 | May 14 | Oct 22 | Oct 6 | 176 days |
| Port Wing | 651 ft | May 31 | Jun 13 | Oct 2 | Sep 17 | 123 days |
| Portage Wwtp | 785 ft | Apr 28 | May 12 | Oct 10 | Sep 26 | 164 days |
| Prairie Du Chien | 658 ft | Apr 28 | May 11 | Oct 12 | Sep 27 | 166 days |
| Prentice #2 | 1,540 ft | May 23 | Jun 6 | Sep 23 | Sep 5 | 124 days |
| Racine | 595 ft | Apr 20 | May 6 | Oct 24 | Oct 8 | 184 days |
| Racine Batten AP | 674 ft | Apr 24 | May 10 | Oct 24 | Oct 10 | 180 days |
| Reedsburg | 926 ft | May 2 | May 16 | Oct 7 | Sep 23 | 156 days |
| Rest Lake | 1,612 ft | May 25 | Jun 9 | Sep 21 | Sep 3 | 117 days |
| Rhinelander | 1,572 ft | May 22 | Jun 4 | Sep 24 | Sep 9 | 125 days |
| Rhinelander 4NE | 1,586 ft | May 23 | Jun 5 | Sep 23 | Sep 7 | 124 days |
| Rhinelander Oneida AP | 1,599 ft | May 26 | Jun 8 | Sep 23 | Sep 5 | 120 days |
| Rice Lake | 1,103 ft | May 8 | May 23 | Oct 2 | Sep 19 | 145 days |
| Rice Rsvr Tomahawk-2 | 1,460 ft | May 10 | May 27 | Oct 4 | Sep 21 | 146 days |
| Richfield 3 Ssw | 984 ft | Apr 30 | May 16 | Oct 16 | Oct 1 | 167 days |
| Richland Ctr | 728 ft | May 5 | May 19 | Oct 6 | Sep 24 | 154 days |
| Ridgeland 1NNE | 1,080 ft | May 10 | May 26 | Sep 29 | Sep 13 | 140 days |
| Ripon 5 Ne | 930 ft | May 1 | May 14 | Oct 11 | Sep 26 | 163 days |
| River Falls | 940 ft | May 11 | May 26 | Oct 1 | Sep 19 | 143 days |
| Rochester Wwtp | 783 ft | May 5 | May 23 | Oct 10 | Sep 26 | 156 days |
| Rock Springs 3 Sw | 1,260 ft | Apr 24 | May 7 | Oct 20 | Oct 1 | 178 days |
| Rosholt 9 Nne | 1,183 ft | May 6 | May 21 | Oct 5 | Sep 22 | 150 days |
| Sauk City Wwtp | 750 ft | May 4 | May 18 | Oct 6 | Sep 23 | 155 days |
| Saukville Wwtp | 766 ft | May 5 | May 19 | Oct 11 | Sep 29 | 158 days |
| Saxon 1WSW | 1,165 ft | May 23 | Jun 5 | Oct 1 | Sep 18 | 132 days |
| Shawano 2SSW | 806 ft | May 9 | May 24 | Oct 2 | Sep 18 | 144 days |
| Sheboygan | 648 ft | Apr 25 | May 11 | Oct 23 | Oct 9 | 179 days |
| Sheboygan Co Mem AP | 746 ft | May 5 | May 21 | Oct 8 | Sep 26 | 154 days |
| Sheboygan Wwtp | 603 ft | May 2 | May 19 | Oct 21 | Oct 3 | 169 days |
| Slinger Wwtp | 1,029 ft | May 5 | May 20 | Oct 5 | Sep 22 | 152 days |
| Solon Springs | 1,130 ft | May 12 | May 27 | Oct 2 | Sep 17 | 142 days |
| South Milwaukee Wwtp | 650 ft | Apr 22 | May 8 | Oct 26 | Oct 10 | 184 days |
| Sparta | 782 ft | May 9 | May 22 | Oct 1 | Sep 18 | 144 days |
| Spooner Ag Res Stn | 1,100 ft | May 14 | May 29 | Sep 28 | Sep 14 | 135 days |
| St Croix Falls | 750 ft | May 4 | May 18 | Oct 8 | Sep 24 | 156 days |
| St Germain | 1,643 ft | May 19 | May 31 | Oct 3 | Sep 18 | 136 days |
| Stanley Wwtp | 1,080 ft | May 7 | May 21 | Oct 3 | Sep 20 | 147 days |
| Steuben 4 Se | 1,015 ft | Apr 22 | May 8 | Oct 20 | Oct 5 | 179 days |
| Stevens Pt | 1,079 ft | May 4 | May 20 | Oct 7 | Sep 24 | 155 days |
| Stockbridge-Munsee Rsvn | 1,050 ft | May 13 | May 26 | Sep 30 | Sep 17 | 141 days |
| Stoughton | 840 ft | Apr 30 | May 15 | Oct 11 | Sep 28 | 163 days |
| Sturgeon Bay Exp Farm | 699 ft | May 8 | May 21 | Oct 13 | Sep 28 | 157 days |
| Sullivan 3SE | 933 ft | May 3 | May 21 | Oct 9 | Sep 25 | 157 days |
| Superior | 607 ft | May 6 | May 25 | Oct 9 | Sep 24 | 154 days |
| Suring | 792 ft | May 14 | May 29 | Oct 1 | Sep 19 | 139 days |
| Town Of Westford | 879 ft | May 1 | May 16 | Oct 11 | Sep 27 | 163 days |
| Trempealeau Dam 6 | 660 ft | Apr 29 | May 13 | Oct 11 | Sep 26 | 165 days |
| Two Rivers | 589 ft | Apr 27 | May 10 | Oct 21 | Oct 4 | 175 days |
| Union Grove | 730 ft | May 5 | May 20 | Oct 8 | Sep 27 | 156 days |
| Uw Arboretum - Madison | 870 ft | May 1 | May 17 | Oct 9 | Sep 26 | 161 days |
| Viroqua | 1,255 ft | May 7 | May 21 | Oct 2 | Sep 18 | 148 days |
| W Bend Public Works | 980 ft | May 1 | May 18 | Oct 12 | Sep 28 | 161 days |
| Washington Is | 686 ft | May 15 | May 31 | Oct 14 | Sep 28 | 152 days |
| Waterloo Wwtp | 800 ft | Apr 30 | May 15 | Oct 9 | Sep 27 | 163 days |
| Watertown Wwtp | 825 ft | Apr 28 | May 13 | Oct 12 | Sep 28 | 167 days |
| Waukesha Wwtp | 789 ft | May 1 | May 18 | Oct 13 | Sep 29 | 162 days |
| Waupaca | 837 ft | May 8 | May 21 | Oct 6 | Sep 23 | 151 days |
| Wausau Dwtn AP | 1,181 ft | May 6 | May 21 | Oct 4 | Sep 21 | 150 days |
| West Allis | 723 ft | Apr 26 | May 12 | Oct 22 | Oct 7 | 177 days |
| West Bend | 940 ft | May 4 | May 21 | Oct 11 | Sep 26 | 157 days |
| Weyerhaeuser 1N | 1,195 ft | May 9 | May 27 | Sep 29 | Sep 14 | 140 days |
| Whitewater | 875 ft | May 2 | May 20 | Oct 9 | Sep 25 | 157 days |
| Willow Rsvr | 1,532 ft | May 13 | May 27 | Oct 3 | Sep 16 | 141 days |
| Winter | 1,355 ft | May 19 | Jun 3 | Sep 27 | Sep 8 | 129 days |
| Wisconsin Dells | 835 ft | May 8 | May 22 | Oct 3 | Sep 21 | 146 days |
| Wisconsin Rapids | 1,033 ft | May 9 | May 24 | Sep 30 | Sep 17 | 142 days |
| Wisconsin Rapids Alexander Fld | 1,019 ft | May 8 | May 22 | Oct 1 | Sep 19 | 145 days |
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