Medicine Bow, WY frost dates
Last spring frostJun 1median date
First fall frostSep 8median date
Growing season99 daysfrost-free
Hardiness zone4aZone 4a
How Medicine Bow compares
- In 8 years out of 10, the last spring frost in Medicine Bow falls between May 20 and June 19, a 30-day window. The first fall frost falls between August 28 and September 20.
- The median last frost is 11 days later than the Wyoming median of May 21.
- Its 99-day growing season is longer than 13% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 20 days later than the zone 4a median of May 12. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4a chart.
- The weather station records an average of 209 nights a year at or below 32°F.
- Compared with Casper, WY, 106 km away, the last frost here is 22 days later than there and the growing season is 43 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 20 |
| 50% (median) | June 1 |
| 10% (safe for tender plants) | June 19 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 28 |
| 50% (median) | September 8 |
| 90% (late) | September 20 |
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 Medicine Bow, WY
Medicine Bow, WY frost dates — last frost Jun 1, first frost Sep 8, zone 4a. whenisthelastfrost.com
Crop
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Start indoors: Mar 9 to Mar 23Transplant outside: May 4 to May 18
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Apr 6 to Apr 20Transplant outside: Jun 8 to Jun 22
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25Sow outdoors: May 4 to Jun 8Plant for fall: Jul 14 to Aug 11
Start indoors: Apr 6 to Apr 20Transplant outside: May 4 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jun 30 to Jul 21
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1
Start indoors: Apr 20 to May 4Transplant outside: Jun 22 to Jul 6Sow outdoors: Jun 22 to Jul 6
Start indoors: Apr 20 to May 4Transplant outside: Jun 8 to Jun 22
Sow outdoors: Apr 20 to May 11Plant for fall: Jun 16 to Jul 7
Sow outdoors: Apr 20 to May 11Plant for fall: Jul 14 to Aug 4
Sow outdoors: Apr 27 to Jun 8Plant for fall: Jul 28 to Aug 18
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 22Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 29
Sow outdoors: May 11 to Jun 8
Sow outdoors: May 11 to Jun 8Plant for fall: Jun 30 to Jul 14
Sow outdoors: May 11 to Jun 1
Sow outdoors: May 18 to Jun 15Plant for fall: Jun 30 to Jul 14
Sow outdoors: May 18 to Jun 8Plant for fall: Jul 14 to Aug 4
Sow outdoors: Jun 8 to Jun 29
Sow outdoors: Jun 8 to Jun 22
Transplant outside: Jun 15 to Jul 6
Plant for fall: Aug 25 to Sep 29
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Medicine Bow, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 9 – Mar 23 | May 4 – May 18 | — | — |
| Peppers | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Eggplant | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Tomatoes | Apr 6 – Apr 20 | Jun 8 – Jun 22 | — | — |
| Lettuce | Apr 6 – Apr 20 | May 11 – May 25 | May 4 – Jun 8 | Jul 14 – Aug 11 |
| Kale | Apr 6 – Apr 20 | May 4 – May 18 | May 4 – May 18 | Jun 30 – Jul 21 |
| Broccoli | Apr 6 – Apr 20 | May 18 – Jun 1 | — | — |
| Cabbage | Apr 6 – Apr 20 | May 11 – May 25 | — | — |
| Cauliflower | Apr 6 – Apr 20 | May 18 – Jun 1 | — | — |
| Okra | Apr 20 – May 4 | Jun 22 – Jul 6 | Jun 22 – Jul 6 | — |
| Basil | Apr 20 – May 4 | Jun 8 – Jun 22 | — | — |
| Peas | — | — | Apr 20 – May 11 | Jun 16 – Jul 7 |
| Spinach | — | — | Apr 20 – May 11 | Jul 14 – Aug 4 |
| Radishes | — | — | Apr 27 – Jun 8 | Jul 28 – Aug 18 |
| Cucumbers | May 4 – May 11 | Jun 15 – Jun 22 | Jun 8 – Jun 22 | — |
| Zucchini & Summer Squash | May 4 – May 11 | — | Jun 8 – Jun 22 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 99 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 4 – May 11 | — | Jun 8 – Jun 22 | — |
| Melons & Watermelon | May 4 – May 11 | Jun 15 – Jun 29 | — | — |
| Carrots | — | — | May 11 – Jun 8 | — |
| Beets | — | — | May 11 – Jun 8 | Jun 30 – Jul 14 |
| Potatoes | — | — | May 11 – Jun 1 | — |
| Swiss Chard | — | — | May 18 – Jun 15 | Jun 30 – Jul 14 |
| Cilantro | — | — | May 18 – Jun 8 | Jul 14 – Aug 4 |
| Green Beans | — | — | Jun 8 – Jun 29 | — |
| Sweet Corn | — | — | Jun 8 – Jun 22 | — |
| Sweet Potatoes Warning: Your frost-free season is about 99 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 15 – Jul 6 | — | — |
| Garlic | — | — | — | Aug 25 – Sep 29 |
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 Medicine Bow, WY weather station, about 1 km away (elevation 6,634 ft (2,022 m)).
Frost dates near Medicine Bow
- Rock River Jun 1 · Sep 8
- Hanna May 28 · Sep 13
- Elk Mountain May 28 · Sep 13
- Garrett Jun 2 · Sep 9
- Walcott Jun 12 · Sep 7
- Bosler Jun 7 · Sep 4
- Saratoga Jun 12 · Sep 7
- Centennial Jun 2 · Sep 19
- Shirley Basin Jun 1 · Sep 15
- Laramie Jun 7 · Sep 4
Frequently asked questions
When is the last frost in Medicine Bow, WY?
The median last spring frost in Medicine Bow, WY is June 1. There is still about a 10% chance of frost after June 19, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Medicine Bow, WY?
The median first fall frost is September 8, with about a 10% chance of frost before August 28.
How long is the growing season in Medicine Bow, WY?
About 99 days between the median last spring frost and first fall frost.
What planting zone is Medicine Bow, WY?
Medicine Bow, WY is in USDA hardiness zone 4a.