Superior, WY frost dates
Last spring frostMay 22median date
First fall frostSep 28median date
Growing season129 daysfrost-free
Hardiness zone5aZone 5a
How Superior compares
- In 8 years out of 10, the last spring frost in Superior falls between May 5 and June 9, a 35-day window. The first fall frost falls between September 14 and October 9.
- The median last frost is 1 day later than the Wyoming median of May 21.
- Its 129-day growing season is longer than 54% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 19 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 189 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 5 |
| 50% (median) | May 22 |
| 10% (safe for tender plants) | June 9 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 14 |
| 50% (median) | September 28 |
| 90% (late) | October 9 |
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 Superior, WY
Superior, WY frost dates — last frost May 22, first frost Sep 28, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 27 to Mar 13Transplant outside: Apr 24 to May 8
Start indoors: Mar 13 to Mar 27Transplant outside: Jun 5 to Jun 19
Start indoors: Mar 13 to Mar 27Transplant outside: Jun 5 to Jun 19
Start indoors: Mar 27 to Apr 10Transplant outside: May 29 to Jun 12
Start indoors: Mar 27 to Apr 10Transplant outside: May 1 to May 15Sow outdoors: Apr 24 to May 29Plant for fall: Aug 3 to Aug 31
Start indoors: Mar 27 to Apr 10Transplant outside: Apr 24 to May 8Sow outdoors: Apr 24 to May 8Plant for fall: Jul 20 to Aug 10
Start indoors: Mar 27 to Apr 10Transplant outside: May 8 to May 22Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 27 to Apr 10Transplant outside: May 1 to May 15Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 27 to Apr 10Transplant outside: May 8 to May 22Plant for fall: Jun 22 to Jul 13
Start indoors: Apr 10 to Apr 24Transplant outside: Jun 12 to Jun 26Sow outdoors: Jun 12 to Jun 26
Start indoors: Apr 10 to Apr 24Transplant outside: May 29 to Jun 12
Sow outdoors: Apr 10 to May 1Plant for fall: Jul 6 to Jul 27
Sow outdoors: Apr 10 to May 1Plant for fall: Aug 3 to Aug 24
Sow outdoors: Apr 17 to May 29Plant for fall: Aug 17 to Sep 7
Start indoors: Apr 24 to May 1Transplant outside: Jun 5 to Jun 12Sow outdoors: May 29 to Jun 12Plant for fall: Jul 13 to Jul 27
Start indoors: Apr 24 to May 1Sow outdoors: May 29 to Jun 12Plant for fall: Jul 20 to Aug 3
Start indoors: Apr 24 to May 1Sow outdoors: May 29 to Jun 12
Start indoors: Apr 24 to May 1Transplant outside: Jun 5 to Jun 19
Sow outdoors: May 1 to May 29Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 1 to May 29Plant for fall: Jul 20 to Aug 3
Sow outdoors: May 1 to May 22
Sow outdoors: May 8 to Jun 5Plant for fall: Jul 20 to Aug 3
Sow outdoors: May 8 to May 29Plant for fall: Aug 3 to Aug 24
Sow outdoors: May 29 to Jun 19Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 29 to Jun 12
Transplant outside: Jun 5 to Jun 26
Plant for fall: Sep 14 to Oct 19
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Superior, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 27 – Mar 13 | Apr 24 – May 8 | — | — |
| Peppers | Mar 13 – Mar 27 | Jun 5 – Jun 19 | — | — |
| Eggplant | Mar 13 – Mar 27 | Jun 5 – Jun 19 | — | — |
| Tomatoes | Mar 27 – Apr 10 | May 29 – Jun 12 | — | — |
| Lettuce | Mar 27 – Apr 10 | May 1 – May 15 | Apr 24 – May 29 | Aug 3 – Aug 31 |
| Kale | Mar 27 – Apr 10 | Apr 24 – May 8 | Apr 24 – May 8 | Jul 20 – Aug 10 |
| Broccoli | Mar 27 – Apr 10 | May 8 – May 22 | — | Jun 22 – Jul 13 |
| Cabbage | Mar 27 – Apr 10 | May 1 – May 15 | — | Jun 22 – Jul 13 |
| Cauliflower | Mar 27 – Apr 10 | May 8 – May 22 | — | Jun 22 – Jul 13 |
| Okra | Apr 10 – Apr 24 | Jun 12 – Jun 26 | Jun 12 – Jun 26 | — |
| Basil | Apr 10 – Apr 24 | May 29 – Jun 12 | — | — |
| Peas | — | — | Apr 10 – May 1 | Jul 6 – Jul 27 |
| Spinach | — | — | Apr 10 – May 1 | Aug 3 – Aug 24 |
| Radishes | — | — | Apr 17 – May 29 | Aug 17 – Sep 7 |
| Cucumbers | Apr 24 – May 1 | Jun 5 – Jun 12 | May 29 – Jun 12 | Jul 13 – Jul 27 |
| Zucchini & Summer Squash | Apr 24 – May 1 | — | May 29 – Jun 12 | Jul 20 – Aug 3 |
| Winter Squash & Pumpkins | Apr 24 – May 1 | — | May 29 – Jun 12 | — |
| Melons & Watermelon | Apr 24 – May 1 | Jun 5 – Jun 19 | — | — |
| Carrots | — | — | May 1 – May 29 | Jul 6 – Jul 20 |
| Beets | — | — | May 1 – May 29 | Jul 20 – Aug 3 |
| Potatoes | — | — | May 1 – May 22 | — |
| Swiss Chard | — | — | May 8 – Jun 5 | Jul 20 – Aug 3 |
| Cilantro | — | — | May 8 – May 29 | Aug 3 – Aug 24 |
| Green Beans | — | — | May 29 – Jun 19 | Jul 13 – Jul 27 |
| Sweet Corn | — | — | May 29 – Jun 12 | — |
| Sweet Potatoes | — | Jun 5 – Jun 26 | — | — |
| Garlic | — | — | — | Sep 14 – Oct 19 |
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 Rock Springs Ap, WY weather station, 20 km away (elevation 6,742 ft (2,055 m)).
Frost dates near Superior
- Point Of Rocks May 22 · Sep 28
- Reliance May 24 · Sep 24
- Rock Springs May 24 · Sep 24
- Green River May 24 · Sep 22
- Farson frost any month
- Wamsutter Jun 5 · Sep 14
- Little America May 25 · Sep 27
- Granger May 25 · Sep 27
- Opal frost any month
- Mc Kinnon May 22 · Sep 29
Frequently asked questions
When is the last frost in Superior, WY?
The median last spring frost in Superior, WY is May 22. There is still about a 10% chance of frost after June 9, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Superior, WY?
The median first fall frost is September 28, with about a 10% chance of frost before September 14.
How long is the growing season in Superior, WY?
About 129 days between the median last spring frost and first fall frost.
What planting zone is Superior, WY?
Superior, WY is in USDA hardiness zone 5a.