Sinclair, WY frost dates
Last spring frostJun 1median date
First fall frostSep 15median date
Growing season106 daysfrost-free
Hardiness zone5aZone 5a
How Sinclair compares
- In 8 years out of 10, the last spring frost in Sinclair falls between May 17 and June 17, a 31-day window. The first fall frost falls between September 3 and September 29.
- The median last frost is 11 days later than the Wyoming median of May 21.
- Its 106-day growing season is longer than 18% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 29 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 192 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 17 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 3 |
| 50% (median) | September 15 |
| 90% (late) | September 29 |
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 Sinclair, WY
Sinclair, WY frost dates — last frost Jun 1, first frost Sep 15, zone 5a. 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 21 to Aug 18
Start indoors: Apr 6 to Apr 20Transplant outside: May 4 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 7 to Jul 28
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 23 to Jul 14
Sow outdoors: Apr 20 to May 11Plant for fall: Jul 21 to Aug 11
Sow outdoors: Apr 27 to Jun 8Plant for fall: Aug 4 to Aug 25
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 22Plant for fall: Jul 7 to Jul 21
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 8Plant for fall: Jun 23 to Jul 7
Sow outdoors: May 11 to Jun 8Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 11 to Jun 1
Sow outdoors: May 18 to Jun 15Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 18 to Jun 8Plant for fall: Jul 21 to Aug 11
Sow outdoors: Jun 8 to Jun 29
Sow outdoors: Jun 8 to Jun 22
Transplant outside: Jun 15 to Jul 6
Plant for fall: Sep 1 to Oct 6
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Sinclair, 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 21 – Aug 18 |
| Kale | Apr 6 – Apr 20 | May 4 – May 18 | May 4 – May 18 | Jul 7 – Jul 28 |
| 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 23 – Jul 14 |
| Spinach | — | — | Apr 20 – May 11 | Jul 21 – Aug 11 |
| Radishes | — | — | Apr 27 – Jun 8 | Aug 4 – Aug 25 |
| Cucumbers | May 4 – May 11 | Jun 15 – Jun 22 | Jun 8 – Jun 22 | — |
| Zucchini & Summer Squash | May 4 – May 11 | — | Jun 8 – Jun 22 | Jul 7 – Jul 21 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 106 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 | Jun 23 – Jul 7 |
| Beets | — | — | May 11 – Jun 8 | Jul 7 – Jul 21 |
| Potatoes | — | — | May 11 – Jun 1 | — |
| Swiss Chard | — | — | May 18 – Jun 15 | Jul 7 – Jul 21 |
| Cilantro | — | — | May 18 – Jun 8 | Jul 21 – Aug 11 |
| Green Beans | — | — | Jun 8 – Jun 29 | — |
| Sweet Corn | — | — | Jun 8 – Jun 22 | — |
| Sweet Potatoes Warning: Your frost-free season is about 106 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 15 – Jul 6 | — | — |
| Garlic | — | — | — | Sep 1 – Oct 6 |
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 Rawlins Muni Ap, WY weather station, 7 km away (elevation 6,736 ft (2,053 m)).
Frost dates near Sinclair
- Rawlins May 17 · Oct 2
- Shirley Basin Jun 1 · Sep 15
- Walcott Jun 12 · Sep 7
- Saratoga Jun 12 · Sep 7
- Hanna May 28 · Sep 13
- Elk Mountain May 28 · Sep 13
- Bairoil May 21 · Sep 27
- Encampment Jun 2 · Sep 12
- Medicine Bow Jun 1 · Sep 8
- Savery Jun 1 · Sep 18
Frequently asked questions
When is the last frost in Sinclair, WY?
The median last spring frost in Sinclair, WY is June 1. There is still about a 10% chance of frost after June 17, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Sinclair, WY?
The median first fall frost is September 15, with about a 10% chance of frost before September 3.
How long is the growing season in Sinclair, WY?
About 106 days between the median last spring frost and first fall frost.
What planting zone is Sinclair, WY?
Sinclair, WY is in USDA hardiness zone 5a.