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Frost Dates and Planting Windows in Wyoming

The 32°F frost dates at the 129 weather stations in Wyoming with NOAA's 1991–2020 Climate Normals, and the planting windows they give. These are long-term statistics, not a forecast. For the dates at the station nearest you, enter your ZIP code.

The planner uses the weather station nearest your ZIP code.

Frost dates across Wyoming

Each risk level uses a date with a set chance of frost. In spring, it's the chance of a 32°F frost on or after the last-frost date. In fall, it's the chance of the first 32°F frost on or before the first-frost date. At the Typical level (30%), the last frost ranges from May 3 to June 30 across the state, and the first frost from August 19 to October 4.

32°F frost dates: earliest and latest among 129 stations, by risk level
Risk levelEarliest last frostLatest last frostEarliest first frostLatest first frost
Conservative (10%)May 11BASIN, WY USJuly 11MOOSE 1 NNE, WY USAugust 8MOOSE 1 NNE, WY USSeptember 26BASIN, WY US
Typical (30%)May 3BASIN, WY USJune 30MOOSE 1 NNE, WY USAugust 19MOOSE 1 NNE, WY USOctober 4BASIN, WY US
Aggressive (50%)April 28BASIN, WY USJune 24MOOSE 1 NNE, WY USAugust 28MOOSE 1 NNE, WY USOctober 10BASIN, WY US

Growing season length

The growing season is the stretch between the last spring frost and the first fall frost at 32°F. NOAA gives it as a length with a chance of being at least that long. Each risk level uses the length with that chance of a shorter season, so Conservative shows the shortest lengths.

Growing season at 32°F: shortest and longest among 129 stations
Risk levelShortestLongest
Conservative (90% chance of at least this long)39 daysMOOSE 1 NNE, WY US144 daysBASIN, WY US
Typical (70% chance of at least this long)54 daysMOOSE 1 NNE, WY US156 daysBASIN, WY US
Aggressive (50% chance of at least this long)63 daysMOOSE 1 NNE, WY US164 daysBASIN, WY US
Number of stations by growing season length, Typical (70% chance of at least this long)
Growing seasonStations
40–59 days1
60–79 days7
80–99 days14
100–119 days51
120–139 days47
140–159 days9

Planting windows across Wyoming

For each crop, the earliest start and the latest end of its Typical windows among the stations. A window at any one station is shorter and falls inside this span. Transplant dates are for seedlings. A fall window is left out at stations where it would start on or before the last day of the spring window, so some rows cover fewer stations.

Typical planting windows (30% frost dates): earliest start and latest end among stations
Crop and taskEarliest startLatest endStations
Basil: Transplant outdoorsMay 17July 14129 of 129
Bean: Sow outdoorsMay 3June 30129 of 129
Beet: Sow outdoorsApril 5June 30129 of 129
Beet: Sow for fallJune 11August 15119 of 129
Broccoli: Transplant outdoorsApril 5June 16129 of 129
Broccoli: Transplant for fallMay 28August 15120 of 129
Brussels sprouts: Transplant outdoorsApril 5June 16129 of 129
Brussels sprouts: Transplant for fallMay 17August 25104 of 129
Cabbage: Transplant outdoorsApril 5June 16129 of 129
Cabbage: Transplant for fallMay 28August 15118 of 129
Cantaloupe: Transplant outdoorsMay 17July 14129 of 129
Cantaloupe: Sow outdoorsMay 17July 14129 of 129
Carrot: Sow outdoorsApril 5June 30129 of 129
Carrot: Sow for fallJune 5August 5112 of 129
Cucumber: Transplant outdoorsMay 10July 7129 of 129
Cucumber: Sow outdoorsMay 3June 30129 of 129
Eggplant: Transplant outdoorsMay 17July 14129 of 129
Garlic: Plant for fallAugust 19October 18129 of 129
Lettuce: Transplant outdoorsApril 5June 16129 of 129
Lettuce: Sow outdoorsApril 5June 16129 of 129
Lettuce: Sow for fallMay 28August 25120 of 129
Onion: Transplant or plant setsApril 5June 16129 of 129
Peas: Sow outdoorsApril 5June 16129 of 129
Peas: Sow for fallJune 4August 15126 of 129
Pepper: Transplant outdoorsMay 17July 14129 of 129
Potato: Plant seed potatoesApril 5June 30129 of 129
Pumpkin: Sow outdoorsMay 17July 14129 of 129
Radish: Sow outdoorsApril 5June 16129 of 129
Radish: Sow for fallJuly 1September 14129 of 129
Spinach: Transplant outdoorsApril 5June 16129 of 129
Spinach: Sow outdoorsApril 5June 16129 of 129
Spinach: Sow for fallJune 14August 28127 of 129
Summer squash: Transplant outdoorsMay 10July 7129 of 129
Summer squash: Sow outdoorsMay 3June 30129 of 129
Sweet corn: Sow outdoorsMay 3June 30129 of 129
Sweet potato: Plant slipsMay 10July 14129 of 129
Tomato: Transplant outdoorsMay 17July 14129 of 129
Turnip: Sow outdoorsApril 5June 16129 of 129
Turnip: Sow for fallJune 14August 25127 of 129
Watermelon: Transplant outdoorsMay 17July 14129 of 129
Watermelon: Sow outdoorsMay 17July 14129 of 129

Weather stations in Wyoming

Every station in Wyoming with NOAA frost-date normals, with its Typical 32°F frost dates and growing season. 29 of them have no 32°F frost dates.

Data sources

NOAA U.S. Climate Normals, frost dates, 1991–2020 normals, version 1.0.1
Files: us-climate-normals_1991-2020_v1.0.1_annualseasonal_multivariate_by-station_c20230404.tar.gz, inventory_30yr.txt from NOAA NCEI. Retrieved October 10, 2026.