Jeffrey City, WY frost dates
Last spring frostJun 1median date
First fall frostSep 13median date
Growing season104 daysfrost-free
Hardiness zone4bZone 4b
How Jeffrey City compares
- In 8 years out of 10, the last spring frost in Jeffrey City falls between May 17 and June 16, a 30-day window. The first fall frost falls between September 1 and September 28.
- The median last frost is 11 days later than the Wyoming median of May 21.
- Its 104-day growing season is longer than 16% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 24 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 207 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 17 |
| 50% (median) | June 1 |
| 10% (safe for tender plants) | June 16 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 1 |
| 50% (median) | September 13 |
| 90% (late) | September 28 |
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 Jeffrey City, WY
Jeffrey City, WY frost dates — last frost Jun 1, first frost Sep 13, zone 4b. whenisthelastfrost.com
Crop
JFMAMJJASOND
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 19 to Aug 16
Start indoors: Apr 6 to Apr 20Transplant outside: May 4 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 5 to Jul 26
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 21 to Jul 12
Sow outdoors: Apr 20 to May 11Plant for fall: Jul 19 to Aug 9
Sow outdoors: Apr 27 to Jun 8Plant for fall: Aug 2 to Aug 23
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: Jul 5 to Jul 19
Sow outdoors: May 11 to Jun 1
Sow outdoors: May 18 to Jun 15Plant for fall: Jul 5 to Jul 19
Sow outdoors: May 18 to Jun 8Plant for fall: Jul 19 to Aug 9
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 30 to Oct 4
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Jeffrey City, 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 19 – Aug 16 |
| Kale | Apr 6 – Apr 20 | May 4 – May 18 | May 4 – May 18 | Jul 5 – Jul 26 |
| 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 21 – Jul 12 |
| Spinach | — | — | Apr 20 – May 11 | Jul 19 – Aug 9 |
| Radishes | — | — | Apr 27 – Jun 8 | Aug 2 – Aug 23 |
| 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 104 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 | Jul 5 – Jul 19 |
| Potatoes | — | — | May 11 – Jun 1 | — |
| Swiss Chard | — | — | May 18 – Jun 15 | Jul 5 – Jul 19 |
| Cilantro | — | — | May 18 – Jun 8 | Jul 19 – Aug 9 |
| Green Beans | — | — | Jun 8 – Jun 29 | — |
| Sweet Corn | — | — | Jun 8 – Jun 22 | — |
| Sweet Potatoes Warning: Your frost-free season is about 104 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 15 – Jul 6 | — | — |
| Garlic | — | — | — | Aug 30 – Oct 4 |
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 Jeffrey City, WY weather station, 6 km away (elevation 6,319 ft (1,926 m)).
Frost dates near Jeffrey City
- Bairoil May 21 · Sep 27
- Riverton May 12 · Sep 24
- Saint Stephens May 12 · Sep 24
- Arapahoe May 16 · Sep 28
- Hudson May 18 · Sep 27
- Lander May 18 · Sep 27
- Hiland May 30 · Sep 22
- Shoshoni May 7 · Oct 3
- Arminto May 30 · Sep 22
- Lysite May 14 · Oct 3
Frequently asked questions
When is the last frost in Jeffrey City, WY?
The median last spring frost in Jeffrey City, WY is June 1. There is still about a 10% chance of frost after June 16, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Jeffrey City, WY?
The median first fall frost is September 13, with about a 10% chance of frost before September 1.
How long is the growing season in Jeffrey City, WY?
About 104 days between the median last spring frost and first fall frost.
What planting zone is Jeffrey City, WY?
Jeffrey City, WY is in USDA hardiness zone 4b.