Afton, WY frost dates
Last spring frostJun 20median date
First fall frostSep 1median date
Growing season73 daysfrost-free
Hardiness zone5bZone 5b
How Afton compares
- In 8 years out of 10, the last spring frost in Afton falls between June 2 and July 7, a 35-day window. The first fall frost falls between August 12 and September 15.
- The median last frost is 30 days later than the Wyoming median of May 21.
- Its 73-day growing season is among the shortest of the 153 Wyoming places with a regular frost season.
- The last frost is 50 days later than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 227 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | June 2 |
| 50% (median) | June 20 |
| 10% (safe for tender plants) | July 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 12 |
| 50% (median) | September 1 |
| 90% (late) | September 15 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Afton, WY
Afton, WY frost dates — last frost Jun 20, first frost Sep 1, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Mar 28 to Apr 11Transplant outside: May 23 to Jun 6
Start indoors: Apr 11 to Apr 25Transplant outside: Jul 4 to Jul 18
Start indoors: Apr 11 to Apr 25Transplant outside: Jul 4 to Jul 18
Start indoors: Apr 25 to May 9Transplant outside: Jun 27 to Jul 11
Start indoors: Apr 25 to May 9Transplant outside: May 30 to Jun 13Sow outdoors: May 23 to Jun 27
Start indoors: Apr 25 to May 9Transplant outside: May 23 to Jun 6Sow outdoors: May 23 to Jun 6
Start indoors: Apr 25 to May 9Transplant outside: Jun 6 to Jun 20
Start indoors: Apr 25 to May 9Transplant outside: May 30 to Jun 13
Start indoors: Apr 25 to May 9Transplant outside: Jun 6 to Jun 20
Start indoors: May 9 to May 23Transplant outside: Jul 11 to Jul 25Sow outdoors: Jul 11 to Jul 25
Start indoors: May 9 to May 23Transplant outside: Jun 27 to Jul 11
Sow outdoors: May 9 to May 30
Sow outdoors: May 9 to May 30Plant for fall: Jul 7 to Jul 28
Sow outdoors: May 16 to Jun 27Plant for fall: Jul 21 to Aug 11
Start indoors: May 23 to May 30Transplant outside: Jul 4 to Jul 11Sow outdoors: Jun 27 to Jul 11
Start indoors: May 23 to May 30Sow outdoors: Jun 27 to Jul 11
Start indoors: May 23 to May 30Sow outdoors: Jun 27 to Jul 11
Start indoors: May 23 to May 30Transplant outside: Jul 4 to Jul 18
Sow outdoors: May 30 to Jun 27
Sow outdoors: May 30 to Jun 27
Sow outdoors: May 30 to Jun 20
Sow outdoors: Jun 6 to Jul 4
Sow outdoors: Jun 6 to Jun 27
Sow outdoors: Jun 27 to Jul 18
Sow outdoors: Jun 27 to Jul 11
Transplant outside: Jul 4 to Jul 25
Plant for fall: Aug 18 to Sep 22
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Afton, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 28 – Apr 11 | May 23 – Jun 6 | — | — |
| Peppers Warning: Your frost-free season is about 73 days, which is tight for peppers (75+ days). Choose early varieties and use transplants or row covers. | Apr 11 – Apr 25 | Jul 4 – Jul 18 | — | — |
| Eggplant Warning: Your frost-free season is about 73 days, which is tight for eggplant (75+ days). Choose early varieties and use transplants or row covers. | Apr 11 – Apr 25 | Jul 4 – Jul 18 | — | — |
| Tomatoes Warning: Your frost-free season is about 73 days, which is tight for tomatoes (70+ days). Choose early varieties and use transplants or row covers. | Apr 25 – May 9 | Jun 27 – Jul 11 | — | — |
| Lettuce | Apr 25 – May 9 | May 30 – Jun 13 | May 23 – Jun 27 | — |
| Kale | Apr 25 – May 9 | May 23 – Jun 6 | May 23 – Jun 6 | — |
| Broccoli | Apr 25 – May 9 | Jun 6 – Jun 20 | — | — |
| Cabbage | Apr 25 – May 9 | May 30 – Jun 13 | — | — |
| Cauliflower | Apr 25 – May 9 | Jun 6 – Jun 20 | — | — |
| Okra Warning: Your frost-free season is about 73 days, which is tight for okra (60+ days). Choose early varieties and use transplants or row covers. | May 9 – May 23 | Jul 11 – Jul 25 | Jul 11 – Jul 25 | — |
| Basil Warning: Your frost-free season is about 73 days, which is tight for basil (60+ days). Choose early varieties and use transplants or row covers. | May 9 – May 23 | Jun 27 – Jul 11 | — | — |
| Peas | — | — | May 9 – May 30 | — |
| Spinach | — | — | May 9 – May 30 | Jul 7 – Jul 28 |
| Radishes | — | — | May 16 – Jun 27 | Jul 21 – Aug 11 |
| Cucumbers | May 23 – May 30 | Jul 4 – Jul 11 | Jun 27 – Jul 11 | — |
| Zucchini & Summer Squash | May 23 – May 30 | — | Jun 27 – Jul 11 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 73 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 23 – May 30 | — | Jun 27 – Jul 11 | — |
| Melons & Watermelon Warning: Your frost-free season is about 73 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 23 – May 30 | Jul 4 – Jul 18 | — | — |
| Carrots | — | — | May 30 – Jun 27 | — |
| Beets | — | — | May 30 – Jun 27 | — |
| Potatoes | — | — | May 30 – Jun 20 | — |
| Swiss Chard | — | — | Jun 6 – Jul 4 | — |
| Cilantro | — | — | Jun 6 – Jun 27 | — |
| Green Beans | — | — | Jun 27 – Jul 18 | — |
| Sweet Corn Warning: Your frost-free season is about 73 days, which is tight for sweet corn (80+ days). Choose early varieties and use transplants or row covers. | — | — | Jun 27 – Jul 11 | — |
| Sweet Potatoes Warning: Your frost-free season is about 73 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jul 4 – Jul 25 | — | — |
| Garlic | — | — | — | Aug 18 – Sep 22 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Afton, WY weather station, 3 km away (elevation 6,247 ft (1,904 m)).
Frost dates near Afton
- Fairview Jun 20 · Sep 1
- Grover Jun 20 · Sep 1
- Smoot Jun 20 · Sep 1
- Auburn Jun 20 · Sep 1
- Bedford frost any month
- Thayne frost any month
- Freedom frost any month
- Etna frost any month
- Alpine frost any month
- Big Piney frost any month
Frequently asked questions
When is the last frost in Afton, WY?
The median last spring frost in Afton, WY is June 20. There is still about a 10% chance of frost after July 7, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Afton, WY?
The median first fall frost is September 1, with about a 10% chance of frost before August 12.
How long is the growing season in Afton, WY?
About 73 days between the median last spring frost and first fall frost.
What planting zone is Afton, WY?
Afton, WY is in USDA hardiness zone 5b.