Arapahoe, WY frost dates
Last spring frostMay 16median date
First fall frostSep 28median date
Growing season135 daysfrost-free
Hardiness zone5aZone 5a
How Arapahoe compares
- In 8 years out of 10, the last spring frost in Arapahoe falls between May 1 and May 31, a 30-day window. The first fall frost falls between September 15 and October 12.
- The median last frost is 5 days earlier than the Wyoming median of May 21.
- Its 135-day growing season is longer than 67% 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 182 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 1 |
| 50% (median) | May 16 |
| 10% (safe for tender plants) | May 31 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 15 |
| 50% (median) | September 28 |
| 90% (late) | October 12 |
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 Arapahoe, WY
Arapahoe, WY frost dates — last frost May 16, first frost Sep 28, 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: Aug 3 to Aug 31
Start indoors: Mar 21 to Apr 4Transplant outside: Apr 18 to May 2Sow outdoors: Apr 18 to May 2Plant for fall: Jul 20 to Aug 10
Start indoors: Mar 21 to Apr 4Transplant outside: May 2 to May 16Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 21 to Apr 4Transplant outside: Apr 25 to May 9Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 21 to Apr 4Transplant outside: May 2 to May 16Plant for fall: Jun 22 to Jul 13
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 6 to Jul 27
Sow outdoors: Apr 4 to Apr 25Plant for fall: Aug 3 to Aug 24
Sow outdoors: Apr 11 to May 23Plant for fall: Aug 17 to Sep 7
Start indoors: Apr 18 to Apr 25Transplant outside: May 30 to Jun 6Sow outdoors: May 23 to Jun 6Plant for fall: Jul 13 to Jul 27
Start indoors: Apr 18 to Apr 25Sow outdoors: May 23 to Jun 6Plant for fall: Jul 20 to Aug 3
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 6 to Jul 20
Sow outdoors: Apr 25 to May 23Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 25 to May 16
Sow outdoors: May 2 to May 30Plant for fall: Jul 20 to Aug 3
Sow outdoors: May 2 to May 23Plant for fall: Aug 3 to Aug 24
Sow outdoors: May 23 to Jun 13Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 23 to Jun 6
Transplant outside: May 30 to Jun 20
Plant for fall: Sep 14 to Oct 19
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Arapahoe, 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 | Aug 3 – Aug 31 |
| Kale | Mar 21 – Apr 4 | Apr 18 – May 2 | Apr 18 – May 2 | Jul 20 – Aug 10 |
| Broccoli | Mar 21 – Apr 4 | May 2 – May 16 | — | Jun 22 – Jul 13 |
| Cabbage | Mar 21 – Apr 4 | Apr 25 – May 9 | — | Jun 22 – Jul 13 |
| Cauliflower | Mar 21 – Apr 4 | May 2 – May 16 | — | Jun 22 – Jul 13 |
| 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 6 – Jul 27 |
| Spinach | — | — | Apr 4 – Apr 25 | Aug 3 – Aug 24 |
| Radishes | — | — | Apr 11 – May 23 | Aug 17 – Sep 7 |
| Cucumbers | Apr 18 – Apr 25 | May 30 – Jun 6 | May 23 – Jun 6 | Jul 13 – Jul 27 |
| Zucchini & Summer Squash | Apr 18 – Apr 25 | — | May 23 – Jun 6 | Jul 20 – Aug 3 |
| 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 6 – Jul 20 |
| Beets | — | — | Apr 25 – May 23 | Jul 20 – Aug 3 |
| Potatoes | — | — | Apr 25 – May 16 | — |
| Swiss Chard | — | — | May 2 – May 30 | Jul 20 – Aug 3 |
| Cilantro | — | — | May 2 – May 23 | Aug 3 – Aug 24 |
| Green Beans | — | — | May 23 – Jun 13 | Jul 13 – Jul 27 |
| Sweet Corn | — | — | May 23 – Jun 6 | — |
| Sweet Potatoes | — | May 30 – Jun 20 | — | — |
| 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 Riverton, WY weather station, 11 km away (elevation 5,568 ft (1,697 m)).
Frost dates near Arapahoe
- Saint Stephens May 12 · Sep 24
- Lander May 18 · Sep 27
- Hudson May 18 · Sep 27
- Riverton May 12 · Sep 24
- Fort Washakie May 18 · Sep 27
- Shoshoni May 7 · Oct 3
- Pavillion May 14 · Sep 30
- Kinnear May 21 · Sep 20
- Jeffrey City Jun 1 · Sep 13
- Crowheart Jun 1 · Sep 14
Frequently asked questions
When is the last frost in Arapahoe, WY?
The median last spring frost in Arapahoe, WY is May 16. There is still about a 10% chance of frost after May 31, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Arapahoe, WY?
The median first fall frost is September 28, with about a 10% chance of frost before September 15.
How long is the growing season in Arapahoe, WY?
About 135 days between the median last spring frost and first fall frost.
What planting zone is Arapahoe, WY?
Arapahoe, WY is in USDA hardiness zone 5a.