Hanna, WY frost dates
Last spring frostMay 28median date
First fall frostSep 13median date
Growing season108 daysfrost-free
Hardiness zone5aZone 5a
How Hanna compares
- In 8 years out of 10, the last spring frost in Hanna falls between May 14 and June 13, a 30-day window. The first fall frost falls between August 30 and October 1.
- The median last frost is 7 days later than the Wyoming median of May 21.
- Its 108-day growing season is longer than 19% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 25 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.
- Compared with Casper, WY, 110 km away, the last frost here is 18 days later than there and the growing season is 34 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 14 |
| 50% (median) | May 28 |
| 10% (safe for tender plants) | June 13 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 30 |
| 50% (median) | September 13 |
| 90% (late) | October 1 |
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 Hanna, WY
Hanna, WY frost dates — last frost May 28, first frost Sep 13, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 30 to May 14
Start indoors: Mar 19 to Apr 2Transplant outside: Jun 11 to Jun 25
Start indoors: Mar 19 to Apr 2Transplant outside: Jun 11 to Jun 25
Start indoors: Apr 2 to Apr 16Transplant outside: Jun 4 to Jun 18
Start indoors: Apr 2 to Apr 16Transplant outside: May 7 to May 21Sow outdoors: Apr 30 to Jun 4Plant for fall: Jul 19 to Aug 16
Start indoors: Apr 2 to Apr 16Transplant outside: Apr 30 to May 14Sow outdoors: Apr 30 to May 14Plant for fall: Jul 5 to Jul 26
Start indoors: Apr 2 to Apr 16Transplant outside: May 14 to May 28
Start indoors: Apr 2 to Apr 16Transplant outside: May 7 to May 21
Start indoors: Apr 2 to Apr 16Transplant outside: May 14 to May 28
Start indoors: Apr 16 to Apr 30Transplant outside: Jun 18 to Jul 2Sow outdoors: Jun 18 to Jul 2
Start indoors: Apr 16 to Apr 30Transplant outside: Jun 4 to Jun 18
Sow outdoors: Apr 16 to May 7Plant for fall: Jun 21 to Jul 12
Sow outdoors: Apr 16 to May 7Plant for fall: Jul 19 to Aug 9
Sow outdoors: Apr 23 to Jun 4Plant for fall: Aug 2 to Aug 23
Start indoors: Apr 30 to May 7Transplant outside: Jun 11 to Jun 18Sow outdoors: Jun 4 to Jun 18
Start indoors: Apr 30 to May 7Sow outdoors: Jun 4 to Jun 18Plant for fall: Jul 5 to Jul 19
Start indoors: Apr 30 to May 7Sow outdoors: Jun 4 to Jun 18
Start indoors: Apr 30 to May 7Transplant outside: Jun 11 to Jun 25
Sow outdoors: May 7 to Jun 4Plant for fall: Jun 21 to Jul 5
Sow outdoors: May 7 to Jun 4Plant for fall: Jul 5 to Jul 19
Sow outdoors: May 7 to May 28
Sow outdoors: May 14 to Jun 11Plant for fall: Jul 5 to Jul 19
Sow outdoors: May 14 to Jun 4Plant for fall: Jul 19 to Aug 9
Sow outdoors: Jun 4 to Jun 25
Sow outdoors: Jun 4 to Jun 18
Transplant outside: Jun 11 to Jul 2
Plant for fall: Aug 30 to Oct 4
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hanna, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 5 – Mar 19 | Apr 30 – May 14 | — | — |
| Peppers | Mar 19 – Apr 2 | Jun 11 – Jun 25 | — | — |
| Eggplant | Mar 19 – Apr 2 | Jun 11 – Jun 25 | — | — |
| Tomatoes | Apr 2 – Apr 16 | Jun 4 – Jun 18 | — | — |
| Lettuce | Apr 2 – Apr 16 | May 7 – May 21 | Apr 30 – Jun 4 | Jul 19 – Aug 16 |
| Kale | Apr 2 – Apr 16 | Apr 30 – May 14 | Apr 30 – May 14 | Jul 5 – Jul 26 |
| Broccoli | Apr 2 – Apr 16 | May 14 – May 28 | — | — |
| Cabbage | Apr 2 – Apr 16 | May 7 – May 21 | — | — |
| Cauliflower | Apr 2 – Apr 16 | May 14 – May 28 | — | — |
| Okra | Apr 16 – Apr 30 | Jun 18 – Jul 2 | Jun 18 – Jul 2 | — |
| Basil | Apr 16 – Apr 30 | Jun 4 – Jun 18 | — | — |
| Peas | — | — | Apr 16 – May 7 | Jun 21 – Jul 12 |
| Spinach | — | — | Apr 16 – May 7 | Jul 19 – Aug 9 |
| Radishes | — | — | Apr 23 – Jun 4 | Aug 2 – Aug 23 |
| Cucumbers | Apr 30 – May 7 | Jun 11 – Jun 18 | Jun 4 – Jun 18 | — |
| Zucchini & Summer Squash | Apr 30 – May 7 | — | Jun 4 – Jun 18 | Jul 5 – Jul 19 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 108 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | Apr 30 – May 7 | — | Jun 4 – Jun 18 | — |
| Melons & Watermelon | Apr 30 – May 7 | Jun 11 – Jun 25 | — | — |
| Carrots | — | — | May 7 – Jun 4 | Jun 21 – Jul 5 |
| Beets | — | — | May 7 – Jun 4 | Jul 5 – Jul 19 |
| Potatoes | — | — | May 7 – May 28 | — |
| Swiss Chard | — | — | May 14 – Jun 11 | Jul 5 – Jul 19 |
| Cilantro | — | — | May 14 – Jun 4 | Jul 19 – Aug 9 |
| Green Beans | — | — | Jun 4 – Jun 25 | — |
| Sweet Corn | — | — | Jun 4 – Jun 18 | — |
| Sweet Potatoes Warning: Your frost-free season is about 108 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 11 – Jul 2 | — | — |
| 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 Elk Mtn, WY weather station, 23 km away (elevation 7,264 ft (2,214 m)).
Frost dates near Hanna
- Elk Mountain May 28 · Sep 13
- Medicine Bow Jun 1 · Sep 8
- Walcott Jun 12 · Sep 7
- Shirley Basin Jun 1 · Sep 15
- Saratoga Jun 12 · Sep 7
- Rock River Jun 1 · Sep 8
- Sinclair Jun 1 · Sep 15
- Rawlins May 17 · Oct 2
- Centennial Jun 2 · Sep 19
- Alcova May 9 · Oct 7
Frequently asked questions
When is the last frost in Hanna, WY?
The median last spring frost in Hanna, WY is May 28. There is still about a 10% chance of frost after June 13, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hanna, WY?
The median first fall frost is September 13, with about a 10% chance of frost before August 30.
How long is the growing season in Hanna, WY?
About 108 days between the median last spring frost and first fall frost.
What planting zone is Hanna, WY?
Hanna, WY is in USDA hardiness zone 5a.