Shell, WY frost dates
Last spring frostMay 16median date
First fall frostSep 24median date
Growing season131 daysfrost-free
Hardiness zone5aZone 5a
How Shell compares
- In 8 years out of 10, the last spring frost in Shell falls between May 4 and June 3, a 30-day window. The first fall frost falls between September 10 and October 7.
- The median last frost is 5 days earlier than the Wyoming median of May 21.
- Its 131-day growing season is longer than 60% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 13 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 198 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 4 |
| 50% (median) | May 16 |
| 10% (safe for tender plants) | June 3 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 10 |
| 50% (median) | September 24 |
| 90% (late) | October 7 |
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 Shell, WY
Shell, WY frost dates — last frost May 16, first frost Sep 24, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 21 to Mar 7Transplant outside: Apr 18 to May 2
Start indoors: Mar 7 to Mar 21Transplant outside: May 30 to Jun 13
Start indoors: Mar 7 to Mar 21Transplant outside: May 30 to Jun 13
Start indoors: Mar 21 to Apr 4Transplant outside: May 23 to Jun 6
Start indoors: Mar 21 to Apr 4Transplant outside: Apr 25 to May 9Sow outdoors: Apr 18 to May 23Plant for fall: Jul 30 to Aug 27
Start indoors: Mar 21 to Apr 4Transplant outside: Apr 18 to May 2Sow outdoors: Apr 18 to May 2Plant for fall: Jul 16 to Aug 6
Start indoors: Mar 21 to Apr 4Transplant outside: May 2 to May 16Plant for fall: Jun 18 to Jul 9
Start indoors: Mar 21 to Apr 4Transplant outside: Apr 25 to May 9Plant for fall: Jun 18 to Jul 9
Start indoors: Mar 21 to Apr 4Transplant outside: May 2 to May 16Plant for fall: Jun 18 to Jul 9
Start indoors: Apr 4 to Apr 18Transplant outside: Jun 6 to Jun 20Sow outdoors: Jun 6 to Jun 20
Start indoors: Apr 4 to Apr 18Transplant outside: May 23 to Jun 6
Sow outdoors: Apr 4 to Apr 25Plant for fall: Jul 2 to Jul 23
Sow outdoors: Apr 4 to Apr 25Plant for fall: Jul 30 to Aug 20
Sow outdoors: Apr 11 to May 23Plant for fall: Aug 13 to Sep 3
Start indoors: Apr 18 to Apr 25Transplant outside: May 30 to Jun 6Sow outdoors: May 23 to Jun 6Plant for fall: Jul 9 to Jul 23
Start indoors: Apr 18 to Apr 25Sow outdoors: May 23 to Jun 6Plant for fall: Jul 16 to Jul 30
Start indoors: Apr 18 to Apr 25Sow outdoors: May 23 to Jun 6
Start indoors: Apr 18 to Apr 25Transplant outside: May 30 to Jun 13
Sow outdoors: Apr 25 to May 23Plant for fall: Jul 2 to Jul 16
Sow outdoors: Apr 25 to May 23Plant for fall: Jul 16 to Jul 30
Sow outdoors: Apr 25 to May 16
Sow outdoors: May 2 to May 30Plant for fall: Jul 16 to Jul 30
Sow outdoors: May 2 to May 23Plant for fall: Jul 30 to Aug 20
Sow outdoors: May 23 to Jun 13Plant for fall: Jul 9 to Jul 23
Sow outdoors: May 23 to Jun 6
Transplant outside: May 30 to Jun 20
Plant for fall: Sep 10 to Oct 15
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Shell, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 21 – Mar 7 | Apr 18 – May 2 | — | — |
| Peppers | Mar 7 – Mar 21 | May 30 – Jun 13 | — | — |
| Eggplant | Mar 7 – Mar 21 | May 30 – Jun 13 | — | — |
| Tomatoes | Mar 21 – Apr 4 | May 23 – Jun 6 | — | — |
| Lettuce | Mar 21 – Apr 4 | Apr 25 – May 9 | Apr 18 – May 23 | Jul 30 – Aug 27 |
| Kale | Mar 21 – Apr 4 | Apr 18 – May 2 | Apr 18 – May 2 | Jul 16 – Aug 6 |
| Broccoli | Mar 21 – Apr 4 | May 2 – May 16 | — | Jun 18 – Jul 9 |
| Cabbage | Mar 21 – Apr 4 | Apr 25 – May 9 | — | Jun 18 – Jul 9 |
| Cauliflower | Mar 21 – Apr 4 | May 2 – May 16 | — | Jun 18 – Jul 9 |
| Okra | Apr 4 – Apr 18 | Jun 6 – Jun 20 | Jun 6 – Jun 20 | — |
| Basil | Apr 4 – Apr 18 | May 23 – Jun 6 | — | — |
| Peas | — | — | Apr 4 – Apr 25 | Jul 2 – Jul 23 |
| Spinach | — | — | Apr 4 – Apr 25 | Jul 30 – Aug 20 |
| Radishes | — | — | Apr 11 – May 23 | Aug 13 – Sep 3 |
| Cucumbers | Apr 18 – Apr 25 | May 30 – Jun 6 | May 23 – Jun 6 | Jul 9 – Jul 23 |
| Zucchini & Summer Squash | Apr 18 – Apr 25 | — | May 23 – Jun 6 | Jul 16 – Jul 30 |
| Winter Squash & Pumpkins | Apr 18 – Apr 25 | — | May 23 – Jun 6 | — |
| Melons & Watermelon | Apr 18 – Apr 25 | May 30 – Jun 13 | — | — |
| Carrots | — | — | Apr 25 – May 23 | Jul 2 – Jul 16 |
| Beets | — | — | Apr 25 – May 23 | Jul 16 – Jul 30 |
| Potatoes | — | — | Apr 25 – May 16 | — |
| Swiss Chard | — | — | May 2 – May 30 | Jul 16 – Jul 30 |
| Cilantro | — | — | May 2 – May 23 | Jul 30 – Aug 20 |
| Green Beans | — | — | May 23 – Jun 13 | Jul 9 – Jul 23 |
| Sweet Corn | — | — | May 23 – Jun 6 | — |
| Sweet Potatoes | — | May 30 – Jun 20 | — | — |
| Garlic | — | — | — | Sep 10 – Oct 15 |
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 Shell, WY weather station, 7 km away (elevation 4,242 ft (1,293 m)).
Frost dates near Shell
- Greybull May 11 · Sep 23
- Basin Apr 28 · Oct 10
- Manderson Apr 28 · Oct 10
- Hyattville May 10 · Oct 1
- Otto May 12 · Sep 28
- Emblem May 12 · Sep 28
- Dayton May 24 · Sep 18
- Wolf May 24 · Sep 18
- Burlington May 12 · Sep 28
- Parkman May 24 · Sep 18
Frequently asked questions
When is the last frost in Shell, WY?
The median last spring frost in Shell, WY is May 16. There is still about a 10% chance of frost after June 3, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Shell, WY?
The median first fall frost is September 24, with about a 10% chance of frost before September 10.
How long is the growing season in Shell, WY?
About 131 days between the median last spring frost and first fall frost.
What planting zone is Shell, WY?
Shell, WY is in USDA hardiness zone 5a.